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slog-v1 #14

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This PR represents a port of the structured-logging-v1 patches that I submitted to the mailing list.
It includes a few fixups from my WIP-V2 branch.

It is based upon the json-writer-v11 patches.
It also includes several GVFS-specific patches to report additional data "config" and "aux" data.

(This PR includes the json-writer commit for now. There is a separate PR for it that should be
merged before this one.)

Add "struct json_writer" and a series of jw_ routines to compose JSON
data into a string buffer.  The resulting string may then be printed by
commands wanting to support a JSON-like output format.

The json_writer is limited to correctly formatting structured data for
output.  It does not attempt to build an object model of the JSON data.

We say "JSON-like" because we do not enforce the Unicode (usually UTF-8)
requirement on string fields.  Internally, Git does not necessarily have
Unicode/UTF-8 data for most fields, so it is currently unclear the best
way to enforce that requirement.  For example, on Linux pathnames can
contain arbitrary 8-bit character data, so a command like "status" would
not know how to encode the reported pathnames.  We may want to revisit
this (or double encode such strings) in the future.

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: René Scharfe <l.s.r@web.de>
Helped-by: Wink Saville <wink@saville.com>
Helped-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach the Makefile to take STRUCTURED_LOGGING=1 variable to
compile in/out structured logging feature.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach git to optionally generate structured logging data in JSON using
the json-writer API.  "cmd_start" and "cmd_end" events are generated.

Structured logging is only available when git is built with
STRUCTURED_LOGGING=1.

Structured logging is only enabled when the config setting "slog.path"
is set to an absolute pathname.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach git to create a unique session id (SID) during structured
logging initialization and use that SID in all log events.

This SID is exported into a transient environment variable and
inherited by child processes.  This allows git child processes
to be related back to the parent git process event if there are
intermediate /bin/sh processes between them.

Update t0001 to ignore the environment variable GIT_SLOG_PARENT_SID.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Set sub-command field for the various forms of the branch command.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Add structured logging prereq definition "SLOG" to test-lib.sh.
Create t0420 test script with some basic tests.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Add a generic "detail-event" to structured logging.  This can be used
to emit context-specific events for performance or debugging purposes.
These are conceptually similar to the various GIT_TRACE_<key> messages.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach git to generate a structured logging detail-event for
lazy_init_name_hash().  This is marked as an "index" category
event and includes time and size data for the hashmaps.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Add timer facility to structured logging.  This allows stopwatch-like
operations over the life of the git process.  Timer data is summarized
in the "cmd_exit" event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Use a SLOG timer to record the time spent in do_read_index()
and report it in the "cmd_exit" event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Use a SLOG timer to record the time spend in do_write_index() and
report it in the "cmd_exit" event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Use a SLOG timer to record the time spend in wt_status_collect_worktree(),
wt_status_collect_changes_initial(), wt_status_collect_changes_index(),
and wt_status_collect_untracked().  These are reported in the "cmd_exit"
event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Use a SLOG timer to record the time spend in preload_index() and
report it in the "cmd_exit" event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Add facility to add extra data to the structured logging data allowing
arbitrary key/value pair data to be added to the "cmd_exit" event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach do_read_index() and do_write_index() to record the size of the index
in aux-data.  This will be reported in the "cmd_exit" event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach unpack_trees() to record the number of entries in the sparse-checkout
file in the aux-data.  This will be reported in the "cmd_exit" event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
remote-curl is not a builtin command and therefore, does not inherit
the common cmd_main() startup in git.c

Wrap cmd_main() with slog_cmd_main() in remote-curl to initialize
logging.

Add slog timers around push, fetch, and list verbs.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach git to emit "detail" events with category "child" before a child
process is started and after it finishes.  These events can be used to
infer time spent by git waiting for child processes to complete.

These events are controlled by the slog.detail config setting.  Set to
true or add the token "child" to it.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Teach git to classify child processes as "editor", "pager", "subprocess",
"alias", "shell", or "other".

Add the child process classification to the child detail events.

Mark child processes of class "editor" or "pager" as interactive in the
child detail event.

Add child summary to cmd_exit event grouping child process by class.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Test running a command with a fake pager and verify that a child_summary
is generated.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Add "config" section to "cmd_exit" event to record important
configuration settings in the log.

Add the value of "slog.detail", "slog.timers", and "slog.aux" config
settings to the log.  These values control the filtering of the log.
Knowing the filter settings can help post-processors reason about
the contents of the log.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Add all "gvfs.*" config settings to the cmd_exit event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Add SLOG timer to capture total/min/max/avg time spent
waiting for an object to be dynamically fetched.  This
will be reported in the "cmd_exit" event.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Add aux data describing results of attempting to deserialize
status data using a status cache.

When deserializing from a file:
    aux.status.deserialize = ( "ok" | "reject" )
    aux.status.deserialize_wait = <iterations>

When deserializing from stdin:
    aux.status.deserialize_stdin = ( "ok" | "reject" )

Status will fallback and run a normal status scan when a "reject"
is reported (unless "--deserialize-wait=fail").  If "ok" is reported,
status was able to use the status cache and avoid scanning the workdir.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
@jeffhostetler jeffhostetler requested a review from dscho July 31, 2018 21:53
ldennington pushed a commit to ldennington/git that referenced this pull request Jun 2, 2021
add_pending_object() populates rev.pending, we need to take care of
clearing it once we're done.

This code is run close to the end of a checkout, therefore this leak
seems like it would have very little impact. See also LSAN output
from t0020 below:

Direct leak of 2048 byte(s) in 1 object(s) allocated from:
    #0 0x49ab79 in realloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3
    microsoft#1 0x9acc46 in xrealloc wrapper.c:126:8
    microsoft#2 0x83e3a3 in add_object_array_with_path object.c:337:3
    microsoft#3 0x8f672a in add_pending_object_with_path revision.c:329:2
    microsoft#4 0x8eaeab in add_pending_object_with_mode revision.c:336:2
    microsoft#5 0x8eae9d in add_pending_object revision.c:342:2
    microsoft#6 0x5154a0 in show_local_changes builtin/checkout.c:602:2
    microsoft#7 0x513b00 in merge_working_tree builtin/checkout.c:979:3
    microsoft#8 0x512cb3 in switch_branches builtin/checkout.c:1242:9
    microsoft#9 0x50f8de in checkout_branch builtin/checkout.c:1646:9
    microsoft#10 0x50ba12 in checkout_main builtin/checkout.c:2003:9
    microsoft#11 0x5086c0 in cmd_checkout builtin/checkout.c:2055:8
    microsoft#12 0x4cd91d in run_builtin git.c:467:11
    microsoft#13 0x4cb5f3 in handle_builtin git.c:719:3
    microsoft#14 0x4ccf47 in run_argv git.c:808:4
    microsoft#15 0x4caf49 in cmd_main git.c:939:19
    microsoft#16 0x69e43e in main common-main.c:52:11
    microsoft#17 0x7f5dd1d50349 in __libc_start_main (/lib64/libc.so.6+0x24349)

SUMMARY: AddressSanitizer: 2048 byte(s) leaked in 1 allocation(s).
Signed-off-by: Andrzej Hunt <ajrhunt@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ldennington pushed a commit to ldennington/git that referenced this pull request Jun 2, 2021
mailinfo.p_hdr_info/s_hdr_info are null-terminated lists of strbuf's,
with entries pointing either to NULL or an allocated strbuf. Therefore
we need to free those strbuf's (and not just the data they contain)
whenever we're done with a given entry. (See handle_header() where those
new strbufs are malloc'd.)

Once we no longer need the list (and not just its entries) we can switch
over to strbuf_list_free() instead of manually iterating over the list,
which takes care of those additional details for us. We can only do this
in clear_mailinfo() - in handle_commit_message() we are only clearing the
array contents but want to reuse the array itself, hence we can't use
strbuf_list_free() there.

However, strbuf_list_free() cannot handle a NULL input, and the lists we
are freeing might be NULL. Therefore we add a NULL check in
strbuf_list_free() to make it safe to use with a NULL input (which is a
pattern used by some of the other *_free() functions around git).

Leak output from t0023:

Direct leak of 72 byte(s) in 3 object(s) allocated from:
    #0 0x49a85d in malloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:145:3
    microsoft#1 0x9ac9f4 in do_xmalloc wrapper.c:41:8
    microsoft#2 0x9ac9ca in xmalloc wrapper.c:62:9
    microsoft#3 0x7f6cf7 in handle_header mailinfo.c:205:10
    microsoft#4 0x7f5abf in check_header mailinfo.c:583:4
    microsoft#5 0x7f5524 in mailinfo mailinfo.c:1197:3
    microsoft#6 0x4dcc95 in parse_mail builtin/am.c:1167:6
    microsoft#7 0x4d9070 in am_run builtin/am.c:1732:12
    microsoft#8 0x4d5b7a in cmd_am builtin/am.c:2398:3
    microsoft#9 0x4cd91d in run_builtin git.c:467:11
    microsoft#10 0x4cb5f3 in handle_builtin git.c:719:3
    microsoft#11 0x4ccf47 in run_argv git.c:808:4
    microsoft#12 0x4caf49 in cmd_main git.c:939:19
    microsoft#13 0x69e43e in main common-main.c:52:11
    microsoft#14 0x7fc1fadfa349 in __libc_start_main (/lib64/libc.so.6+0x24349)

SUMMARY: AddressSanitizer: 72 byte(s) leaked in 3 allocation(s).

Signed-off-by: Andrzej Hunt <ajrhunt@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ldennington pushed a commit to ldennington/git that referenced this pull request Jun 2, 2021
sorting might be a list allocated in ref_default_sorting() (in this case
it's a fixed single item list, which has nevertheless been xcalloc'd),
or it might be a list allocated in parse_opt_ref_sorting(). In either
case we could free these lists - but instead we UNLEAK as we're at the
end of cmd_for_each_ref. (There's no existing implementation of
clear_ref_sorting(), and writing a loop to free the list seems more
trouble than it's worth.)

filter.with_commit/no_commit are populated via
OPT_CONTAINS/OPT_NO_CONTAINS, both of which create new entries via
parse_opt_commits(), and also need to be free'd or UNLEAK'd. Because
free_commit_list() already exists, we choose to use that over an UNLEAK.

LSAN output from t0041:

Direct leak of 16 byte(s) in 1 object(s) allocated from:
    #0 0x49a9d2 in calloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:154:3
    microsoft#1 0x9ac252 in xcalloc wrapper.c:140:8
    microsoft#2 0x8a4a55 in ref_default_sorting ref-filter.c:2486:32
    microsoft#3 0x56c6b1 in cmd_for_each_ref builtin/for-each-ref.c:72:13
    microsoft#4 0x4cd91d in run_builtin git.c:467:11
    microsoft#5 0x4cb5f3 in handle_builtin git.c:719:3
    microsoft#6 0x4ccf47 in run_argv git.c:808:4
    microsoft#7 0x4caf49 in cmd_main git.c:939:19
    microsoft#8 0x69dabe in main common-main.c:52:11
    microsoft#9 0x7f2bdc570349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Direct leak of 16 byte(s) in 1 object(s) allocated from:
    #0 0x49a85d in malloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:145:3
    microsoft#1 0x9abf54 in do_xmalloc wrapper.c:41:8
    microsoft#2 0x9abf2a in xmalloc wrapper.c:62:9
    microsoft#3 0x717486 in commit_list_insert commit.c:540:33
    microsoft#4 0x8644cf in parse_opt_commits parse-options-cb.c:98:2
    microsoft#5 0x869bb5 in get_value parse-options.c:181:11
    microsoft#6 0x8677dc in parse_long_opt parse-options.c:378:10
    microsoft#7 0x8659bd in parse_options_step parse-options.c:817:11
    microsoft#8 0x867fcd in parse_options parse-options.c:870:10
    microsoft#9 0x56c62b in cmd_for_each_ref builtin/for-each-ref.c:59:2
    microsoft#10 0x4cd91d in run_builtin git.c:467:11
    microsoft#11 0x4cb5f3 in handle_builtin git.c:719:3
    microsoft#12 0x4ccf47 in run_argv git.c:808:4
    microsoft#13 0x4caf49 in cmd_main git.c:939:19
    microsoft#14 0x69dabe in main common-main.c:52:11
    microsoft#15 0x7f2bdc570349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Signed-off-by: Andrzej Hunt <ajrhunt@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ldennington pushed a commit to ldennington/git that referenced this pull request Jun 2, 2021
parse_pathspec() populates pathspec, hence we need to clear it once it's
no longer needed. seen is xcalloc'd within the same function and
likewise needs to be freed once its no longer needed.

cmd_rm() has multiple early returns, therefore we need to clear or free
as soon as this data is no longer needed, as opposed to doing a cleanup
at the end.

LSAN output from t0020:

Direct leak of 112 byte(s) in 1 object(s) allocated from:
    #0 0x49a85d in malloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:145:3
    microsoft#1 0x9ac0a4 in do_xmalloc wrapper.c:41:8
    microsoft#2 0x9ac07a in xmalloc wrapper.c:62:9
    microsoft#3 0x873277 in parse_pathspec pathspec.c:582:2
    microsoft#4 0x646ffa in cmd_rm builtin/rm.c:266:2
    microsoft#5 0x4cd91d in run_builtin git.c:467:11
    microsoft#6 0x4cb5f3 in handle_builtin git.c:719:3
    microsoft#7 0x4ccf47 in run_argv git.c:808:4
    microsoft#8 0x4caf49 in cmd_main git.c:939:19
    microsoft#9 0x69dc0e in main common-main.c:52:11
    microsoft#10 0x7f948825b349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Indirect leak of 65 byte(s) in 1 object(s) allocated from:
    #0 0x49ab79 in realloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:164:3
    microsoft#1 0x9ac2a6 in xrealloc wrapper.c:126:8
    microsoft#2 0x93b14d in strbuf_grow strbuf.c:98:2
    microsoft#3 0x93ccf6 in strbuf_vaddf strbuf.c:392:3
    microsoft#4 0x93f726 in xstrvfmt strbuf.c:979:2
    microsoft#5 0x93f8b3 in xstrfmt strbuf.c:989:8
    microsoft#6 0x92ad8a in prefix_path_gently setup.c:115:15
    microsoft#7 0x873a8d in init_pathspec_item pathspec.c:439:11
    microsoft#8 0x87334f in parse_pathspec pathspec.c:589:3
    microsoft#9 0x646ffa in cmd_rm builtin/rm.c:266:2
    microsoft#10 0x4cd91d in run_builtin git.c:467:11
    microsoft#11 0x4cb5f3 in handle_builtin git.c:719:3
    microsoft#12 0x4ccf47 in run_argv git.c:808:4
    microsoft#13 0x4caf49 in cmd_main git.c:939:19
    microsoft#14 0x69dc0e in main common-main.c:52:11
    microsoft#15 0x7f948825b349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Indirect leak of 15 byte(s) in 1 object(s) allocated from:
    #0 0x486834 in strdup ../projects/compiler-rt/lib/asan/asan_interceptors.cpp:452:3
    microsoft#1 0x9ac048 in xstrdup wrapper.c:29:14
    microsoft#2 0x873ba2 in init_pathspec_item pathspec.c:468:20
    microsoft#3 0x87334f in parse_pathspec pathspec.c:589:3
    microsoft#4 0x646ffa in cmd_rm builtin/rm.c:266:2
    microsoft#5 0x4cd91d in run_builtin git.c:467:11
    microsoft#6 0x4cb5f3 in handle_builtin git.c:719:3
    microsoft#7 0x4ccf47 in run_argv git.c:808:4
    microsoft#8 0x4caf49 in cmd_main git.c:939:19
    microsoft#9 0x69dc0e in main common-main.c:52:11
    microsoft#10 0x7f948825b349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Direct leak of 1 byte(s) in 1 object(s) allocated from:
    #0 0x49a9d2 in calloc ../projects/compiler-rt/lib/asan/asan_malloc_linux.cpp:154:3
    microsoft#1 0x9ac392 in xcalloc wrapper.c:140:8
    microsoft#2 0x647108 in cmd_rm builtin/rm.c:294:9
    microsoft#3 0x4cd91d in run_builtin git.c:467:11
    microsoft#4 0x4cb5f3 in handle_builtin git.c:719:3
    microsoft#5 0x4ccf47 in run_argv git.c:808:4
    microsoft#6 0x4caf49 in cmd_main git.c:939:19
    microsoft#7 0x69dbfe in main common-main.c:52:11
    microsoft#8 0x7f4fac1b0349 in __libc_start_main (/lib64/libc.so.6+0x24349)

Signed-off-by: Andrzej Hunt <ajrhunt@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
derrickstolee pushed a commit that referenced this pull request Oct 7, 2021
In a sparse index it is possible for the tree that is being verified
to be freed while it is being verified. This happens when the index is
sparse but the cache tree is not and index_name_pos() looks up a path
from the cache tree that is a descendant of a sparse index entry. That
triggers a call to ensure_full_index() which frees the cache tree that
is being verified.  Carrying on trying to verify the tree after this
results in a use-after-free bug. Instead restart the verification if a
sparse index is converted to a full index. This bug is triggered by a
call to reset_head() in "git rebase --apply". Thanks to René Scharfe
and Derrick Stolee for their help analyzing the problem.

==74345==ERROR: AddressSanitizer: heap-use-after-free on address 0x606000001b20 at pc 0x557cbe82d3a2 bp 0x7ffdfee08090 sp 0x7ffdfee08080
READ of size 4 at 0x606000001b20 thread T0
    #0 0x557cbe82d3a1 in verify_one /home/phil/src/git/cache-tree.c:863
    #1 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #2 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #3 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #4 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
    #5 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
    #6 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
    #7 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    #8 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    #9 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    #10 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    #11 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    #12 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    #13 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
    #14 0x557cbe5bcb8d in _start (/home/phil/src/git/git+0x1b9b8d)

0x606000001b20 is located 0 bytes inside of 56-byte region [0x606000001b20,0x606000001b58)
freed by thread T0 here:
    #0 0x7fdd4bacff19 in __interceptor_free /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:127
    #1 0x557cbe82af60 in cache_tree_free /home/phil/src/git/cache-tree.c:35
    #2 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    #3 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    #4 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    #5 0x557cbeb2557a in ensure_full_index /home/phil/src/git/sparse-index.c:310
    #6 0x557cbea45c4a in index_name_stage_pos /home/phil/src/git/read-cache.c:588
    #7 0x557cbe82ce37 in verify_one /home/phil/src/git/cache-tree.c:850
    #8 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #9 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #10 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #11 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
    #12 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
    #13 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
    #14 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    #15 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    #16 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    #17 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    #18 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    #19 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    #20 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

previously allocated by thread T0 here:
    #0 0x7fdd4bad0459 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x557cbebc1807 in xcalloc /home/phil/src/git/wrapper.c:140
    #2 0x557cbe82b7d8 in cache_tree /home/phil/src/git/cache-tree.c:17
    #3 0x557cbe82b7d8 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:763
    #4 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
    #5 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
    #6 0x557cbe8304e1 in prime_cache_tree /home/phil/src/git/cache-tree.c:779
    #7 0x557cbeab7fa7 in reset_head /home/phil/src/git/reset.c:85
    #8 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    #9 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    #10 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    #11 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    #12 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    #13 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    #14 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
derrickstolee added a commit that referenced this pull request Oct 26, 2021
When I was playing around with trace2 data and creating flamegraphs, I tried a `git fetch` call to see how the `git-remote-https` command would show up. What I didn't expect was an `ensure_full_index()` region!

It turns out that `git fetch` and `git pull` need to check the index for a `.gitmodules` file to see if it should recurse into any submodules. Here is the stack trace from a debugger:

```
#0  ensure_full_index (istate=0x555555ac1c80 <the_index>) at sparse-index.c:404
#1  0x000055555571a979 in do_read_index (istate=istate@entry=0x555555ac1c80 <the_index>, path=path@entry=0x555555ad7b90 ".git/index", must_exist=must_exist@entry=0) at read-cache.c:2386
#2  0x000055555571eb7d in do_read_index (must_exist=0, path=0x555555ad7b90 ".git/index", istate=0x555555ac1c80 <the_index>) at hash.h:244
#3  read_index_from (istate=0x555555ac1c80 <the_index>, path=0x555555ad7b90 ".git/index", gitdir=0x555555ad7b30 ".git") at read-cache.c:2426
#4  0x000055555573f4c2 in repo_read_index (repo=repo@entry=0x555555ac1da0 <the_repo>) at repository.c:286
#5  0x00005555556f14d0 in get_oid_with_context_1 (repo=repo@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", flags=flags@entry=0, prefix=prefix@entry=0x0, 
    oid=oid@entry=0x7fffffffdb00, oc=oc@entry=0x7fffffffda70) at object-name.c:1850
#6  0x00005555556f1f53 in get_oid_with_context (oc=0x7fffffffda70, oid=0x7fffffffdb00, flags=0, str=0x55555582c022 ":.gitmodules", repo=0x555555ac1da0 <the_repo>) at object-name.c:1947
#7  repo_get_oid (r=r@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", oid=oid@entry=0x7fffffffdb00) at object-name.c:1603
#8  0x000055555577330f in config_from_gitmodules (fn=fn@entry=0x555555773460 <gitmodules_fetch_config>, repo=0x555555ac1da0 <the_repo>, data=data@entry=0x7fffffffdb60) at submodule-config.c:650
#9  0x000055555577462d in config_from_gitmodules (data=0x7fffffffdb60, repo=<optimized out>, fn=0x555555773460 <gitmodules_fetch_config>) at submodule-config.c:638
#10 fetch_config_from_gitmodules (max_children=<optimized out>, recurse_submodules=<optimized out>) at submodule-config.c:800
#11 0x00005555555b9e41 in cmd_fetch (argc=1, argv=0x7fffffffe090, prefix=0x0) at builtin/fetch.c:1999
#12 0x0000555555573ff6 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:528
#13 handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:785
#14 0x000055555557528c in run_argv (argv=0x7fffffffddf0, argcp=0x7fffffffddfc) at git.c:857
#15 cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:993
#16 0x0000555555573ac8 in main (argc=3, argv=0x7fffffffe088) at common-main.c:52
```

The operations these commands use are guarded by items such as `index_name_pos()` and others. Since the `.gitmodules` file is always at root, we would not need to expand, anyway.
neerajsi-msft pushed a commit to neerajsi-msft/git that referenced this pull request Oct 26, 2021
In a sparse index it is possible for the tree that is being verified
to be freed while it is being verified. This happens when the index is
sparse but the cache tree is not and index_name_pos() looks up a path
from the cache tree that is a descendant of a sparse index entry. That
triggers a call to ensure_full_index() which frees the cache tree that
is being verified.  Carrying on trying to verify the tree after this
results in a use-after-free bug. Instead restart the verification if a
sparse index is converted to a full index. This bug is triggered by a
call to reset_head() in "git rebase --apply". Thanks to René Scharfe
and Derrick Stolee for their help analyzing the problem.

==74345==ERROR: AddressSanitizer: heap-use-after-free on address 0x606000001b20 at pc 0x557cbe82d3a2 bp 0x7ffdfee08090 sp 0x7ffdfee08080
READ of size 4 at 0x606000001b20 thread T0
    #0 0x557cbe82d3a1 in verify_one /home/phil/src/git/cache-tree.c:863
    #1 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    microsoft#2 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    microsoft#3 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    microsoft#4 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
    microsoft#5 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
    microsoft#6 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
    microsoft#7 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    microsoft#8 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    microsoft#9 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    microsoft#10 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    microsoft#11 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    microsoft#12 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    microsoft#13 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
    microsoft#14 0x557cbe5bcb8d in _start (/home/phil/src/git/git+0x1b9b8d)

0x606000001b20 is located 0 bytes inside of 56-byte region [0x606000001b20,0x606000001b58)
freed by thread T0 here:
    #0 0x7fdd4bacff19 in __interceptor_free /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:127
    #1 0x557cbe82af60 in cache_tree_free /home/phil/src/git/cache-tree.c:35
    microsoft#2 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    microsoft#3 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    microsoft#4 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    microsoft#5 0x557cbeb2557a in ensure_full_index /home/phil/src/git/sparse-index.c:310
    microsoft#6 0x557cbea45c4a in index_name_stage_pos /home/phil/src/git/read-cache.c:588
    microsoft#7 0x557cbe82ce37 in verify_one /home/phil/src/git/cache-tree.c:850
    microsoft#8 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    microsoft#9 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    microsoft#10 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    microsoft#11 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
    microsoft#12 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
    microsoft#13 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
    microsoft#14 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    microsoft#15 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    microsoft#16 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    microsoft#17 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    microsoft#18 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    microsoft#19 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    microsoft#20 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

previously allocated by thread T0 here:
    #0 0x7fdd4bad0459 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x557cbebc1807 in xcalloc /home/phil/src/git/wrapper.c:140
    microsoft#2 0x557cbe82b7d8 in cache_tree /home/phil/src/git/cache-tree.c:17
    microsoft#3 0x557cbe82b7d8 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:763
    microsoft#4 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
    microsoft#5 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
    microsoft#6 0x557cbe8304e1 in prime_cache_tree /home/phil/src/git/cache-tree.c:779
    microsoft#7 0x557cbeab7fa7 in reset_head /home/phil/src/git/reset.c:85
    microsoft#8 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    microsoft#9 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    microsoft#10 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    microsoft#11 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    microsoft#12 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    microsoft#13 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    microsoft#14 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
dscho pushed a commit that referenced this pull request Oct 30, 2021
In a sparse index it is possible for the tree that is being verified
to be freed while it is being verified. This happens when the index is
sparse but the cache tree is not and index_name_pos() looks up a path
from the cache tree that is a descendant of a sparse index entry. That
triggers a call to ensure_full_index() which frees the cache tree that
is being verified.  Carrying on trying to verify the tree after this
results in a use-after-free bug. Instead restart the verification if a
sparse index is converted to a full index. This bug is triggered by a
call to reset_head() in "git rebase --apply". Thanks to René Scharfe
and Derrick Stolee for their help analyzing the problem.

==74345==ERROR: AddressSanitizer: heap-use-after-free on address 0x606000001b20 at pc 0x557cbe82d3a2 bp 0x7ffdfee08090 sp 0x7ffdfee08080
READ of size 4 at 0x606000001b20 thread T0
    #0 0x557cbe82d3a1 in verify_one /home/phil/src/git/cache-tree.c:863
    #1 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #2 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #3 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #4 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
    #5 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
    #6 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
    #7 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    #8 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    #9 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    #10 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    #11 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    #12 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    #13 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
    #14 0x557cbe5bcb8d in _start (/home/phil/src/git/git+0x1b9b8d)

0x606000001b20 is located 0 bytes inside of 56-byte region [0x606000001b20,0x606000001b58)
freed by thread T0 here:
    #0 0x7fdd4bacff19 in __interceptor_free /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:127
    #1 0x557cbe82af60 in cache_tree_free /home/phil/src/git/cache-tree.c:35
    #2 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    #3 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    #4 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    #5 0x557cbeb2557a in ensure_full_index /home/phil/src/git/sparse-index.c:310
    #6 0x557cbea45c4a in index_name_stage_pos /home/phil/src/git/read-cache.c:588
    #7 0x557cbe82ce37 in verify_one /home/phil/src/git/cache-tree.c:850
    #8 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #9 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #10 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #11 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
    #12 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
    #13 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
    #14 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    #15 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    #16 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    #17 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    #18 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    #19 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    #20 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

previously allocated by thread T0 here:
    #0 0x7fdd4bad0459 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x557cbebc1807 in xcalloc /home/phil/src/git/wrapper.c:140
    #2 0x557cbe82b7d8 in cache_tree /home/phil/src/git/cache-tree.c:17
    #3 0x557cbe82b7d8 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:763
    #4 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
    #5 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
    #6 0x557cbe8304e1 in prime_cache_tree /home/phil/src/git/cache-tree.c:779
    #7 0x557cbeab7fa7 in reset_head /home/phil/src/git/reset.c:85
    #8 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    #9 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    #10 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    #11 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    #12 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    #13 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    #14 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
dscho pushed a commit that referenced this pull request Oct 30, 2021
When I was playing around with trace2 data and creating flamegraphs, I tried a `git fetch` call to see how the `git-remote-https` command would show up. What I didn't expect was an `ensure_full_index()` region!

It turns out that `git fetch` and `git pull` need to check the index for a `.gitmodules` file to see if it should recurse into any submodules. Here is the stack trace from a debugger:

```
#0  ensure_full_index (istate=0x555555ac1c80 <the_index>) at sparse-index.c:404
#1  0x000055555571a979 in do_read_index (istate=istate@entry=0x555555ac1c80 <the_index>, path=path@entry=0x555555ad7b90 ".git/index", must_exist=must_exist@entry=0) at read-cache.c:2386
#2  0x000055555571eb7d in do_read_index (must_exist=0, path=0x555555ad7b90 ".git/index", istate=0x555555ac1c80 <the_index>) at hash.h:244
#3  read_index_from (istate=0x555555ac1c80 <the_index>, path=0x555555ad7b90 ".git/index", gitdir=0x555555ad7b30 ".git") at read-cache.c:2426
#4  0x000055555573f4c2 in repo_read_index (repo=repo@entry=0x555555ac1da0 <the_repo>) at repository.c:286
#5  0x00005555556f14d0 in get_oid_with_context_1 (repo=repo@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", flags=flags@entry=0, prefix=prefix@entry=0x0, 
    oid=oid@entry=0x7fffffffdb00, oc=oc@entry=0x7fffffffda70) at object-name.c:1850
#6  0x00005555556f1f53 in get_oid_with_context (oc=0x7fffffffda70, oid=0x7fffffffdb00, flags=0, str=0x55555582c022 ":.gitmodules", repo=0x555555ac1da0 <the_repo>) at object-name.c:1947
#7  repo_get_oid (r=r@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", oid=oid@entry=0x7fffffffdb00) at object-name.c:1603
#8  0x000055555577330f in config_from_gitmodules (fn=fn@entry=0x555555773460 <gitmodules_fetch_config>, repo=0x555555ac1da0 <the_repo>, data=data@entry=0x7fffffffdb60) at submodule-config.c:650
#9  0x000055555577462d in config_from_gitmodules (data=0x7fffffffdb60, repo=<optimized out>, fn=0x555555773460 <gitmodules_fetch_config>) at submodule-config.c:638
#10 fetch_config_from_gitmodules (max_children=<optimized out>, recurse_submodules=<optimized out>) at submodule-config.c:800
#11 0x00005555555b9e41 in cmd_fetch (argc=1, argv=0x7fffffffe090, prefix=0x0) at builtin/fetch.c:1999
#12 0x0000555555573ff6 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:528
#13 handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:785
#14 0x000055555557528c in run_argv (argv=0x7fffffffddf0, argcp=0x7fffffffddfc) at git.c:857
#15 cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:993
#16 0x0000555555573ac8 in main (argc=3, argv=0x7fffffffe088) at common-main.c:52
```

The operations these commands use are guarded by items such as `index_name_pos()` and others. Since the `.gitmodules` file is always at root, we would not need to expand, anyway.
derrickstolee added a commit that referenced this pull request Oct 30, 2021
When I was playing around with trace2 data and creating flamegraphs, I tried a `git fetch` call to see how the `git-remote-https` command would show up. What I didn't expect was an `ensure_full_index()` region!

It turns out that `git fetch` and `git pull` need to check the index for a `.gitmodules` file to see if it should recurse into any submodules. Here is the stack trace from a debugger:

```
#0  ensure_full_index (istate=0x555555ac1c80 <the_index>) at sparse-index.c:404
#1  0x000055555571a979 in do_read_index (istate=istate@entry=0x555555ac1c80 <the_index>, path=path@entry=0x555555ad7b90 ".git/index", must_exist=must_exist@entry=0) at read-cache.c:2386
#2  0x000055555571eb7d in do_read_index (must_exist=0, path=0x555555ad7b90 ".git/index", istate=0x555555ac1c80 <the_index>) at hash.h:244
#3  read_index_from (istate=0x555555ac1c80 <the_index>, path=0x555555ad7b90 ".git/index", gitdir=0x555555ad7b30 ".git") at read-cache.c:2426
#4  0x000055555573f4c2 in repo_read_index (repo=repo@entry=0x555555ac1da0 <the_repo>) at repository.c:286
#5  0x00005555556f14d0 in get_oid_with_context_1 (repo=repo@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", flags=flags@entry=0, prefix=prefix@entry=0x0, 
    oid=oid@entry=0x7fffffffdb00, oc=oc@entry=0x7fffffffda70) at object-name.c:1850
#6  0x00005555556f1f53 in get_oid_with_context (oc=0x7fffffffda70, oid=0x7fffffffdb00, flags=0, str=0x55555582c022 ":.gitmodules", repo=0x555555ac1da0 <the_repo>) at object-name.c:1947
#7  repo_get_oid (r=r@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", oid=oid@entry=0x7fffffffdb00) at object-name.c:1603
#8  0x000055555577330f in config_from_gitmodules (fn=fn@entry=0x555555773460 <gitmodules_fetch_config>, repo=0x555555ac1da0 <the_repo>, data=data@entry=0x7fffffffdb60) at submodule-config.c:650
#9  0x000055555577462d in config_from_gitmodules (data=0x7fffffffdb60, repo=<optimized out>, fn=0x555555773460 <gitmodules_fetch_config>) at submodule-config.c:638
#10 fetch_config_from_gitmodules (max_children=<optimized out>, recurse_submodules=<optimized out>) at submodule-config.c:800
#11 0x00005555555b9e41 in cmd_fetch (argc=1, argv=0x7fffffffe090, prefix=0x0) at builtin/fetch.c:1999
#12 0x0000555555573ff6 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:528
#13 handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:785
#14 0x000055555557528c in run_argv (argv=0x7fffffffddf0, argcp=0x7fffffffddfc) at git.c:857
#15 cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:993
#16 0x0000555555573ac8 in main (argc=3, argv=0x7fffffffe088) at common-main.c:52
```

The operations these commands use are guarded by items such as `index_name_pos()` and others. Since the `.gitmodules` file is always at root, we would not need to expand, anyway.
derrickstolee added a commit that referenced this pull request Oct 31, 2021
When I was playing around with trace2 data and creating flamegraphs, I tried a `git fetch` call to see how the `git-remote-https` command would show up. What I didn't expect was an `ensure_full_index()` region!

It turns out that `git fetch` and `git pull` need to check the index for a `.gitmodules` file to see if it should recurse into any submodules. Here is the stack trace from a debugger:

```
#0  ensure_full_index (istate=0x555555ac1c80 <the_index>) at sparse-index.c:404
#1  0x000055555571a979 in do_read_index (istate=istate@entry=0x555555ac1c80 <the_index>, path=path@entry=0x555555ad7b90 ".git/index", must_exist=must_exist@entry=0) at read-cache.c:2386
#2  0x000055555571eb7d in do_read_index (must_exist=0, path=0x555555ad7b90 ".git/index", istate=0x555555ac1c80 <the_index>) at hash.h:244
#3  read_index_from (istate=0x555555ac1c80 <the_index>, path=0x555555ad7b90 ".git/index", gitdir=0x555555ad7b30 ".git") at read-cache.c:2426
#4  0x000055555573f4c2 in repo_read_index (repo=repo@entry=0x555555ac1da0 <the_repo>) at repository.c:286
#5  0x00005555556f14d0 in get_oid_with_context_1 (repo=repo@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", flags=flags@entry=0, prefix=prefix@entry=0x0, 
    oid=oid@entry=0x7fffffffdb00, oc=oc@entry=0x7fffffffda70) at object-name.c:1850
#6  0x00005555556f1f53 in get_oid_with_context (oc=0x7fffffffda70, oid=0x7fffffffdb00, flags=0, str=0x55555582c022 ":.gitmodules", repo=0x555555ac1da0 <the_repo>) at object-name.c:1947
#7  repo_get_oid (r=r@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", oid=oid@entry=0x7fffffffdb00) at object-name.c:1603
#8  0x000055555577330f in config_from_gitmodules (fn=fn@entry=0x555555773460 <gitmodules_fetch_config>, repo=0x555555ac1da0 <the_repo>, data=data@entry=0x7fffffffdb60) at submodule-config.c:650
#9  0x000055555577462d in config_from_gitmodules (data=0x7fffffffdb60, repo=<optimized out>, fn=0x555555773460 <gitmodules_fetch_config>) at submodule-config.c:638
#10 fetch_config_from_gitmodules (max_children=<optimized out>, recurse_submodules=<optimized out>) at submodule-config.c:800
#11 0x00005555555b9e41 in cmd_fetch (argc=1, argv=0x7fffffffe090, prefix=0x0) at builtin/fetch.c:1999
#12 0x0000555555573ff6 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:528
#13 handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:785
#14 0x000055555557528c in run_argv (argv=0x7fffffffddf0, argcp=0x7fffffffddfc) at git.c:857
#15 cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:993
#16 0x0000555555573ac8 in main (argc=3, argv=0x7fffffffe088) at common-main.c:52
```

The operations these commands use are guarded by items such as `index_name_pos()` and others. Since the `.gitmodules` file is always at root, we would not need to expand, anyway.
derrickstolee added a commit that referenced this pull request Nov 4, 2021
When I was playing around with trace2 data and creating flamegraphs, I tried a `git fetch` call to see how the `git-remote-https` command would show up. What I didn't expect was an `ensure_full_index()` region!

It turns out that `git fetch` and `git pull` need to check the index for a `.gitmodules` file to see if it should recurse into any submodules. Here is the stack trace from a debugger:

```
#0  ensure_full_index (istate=0x555555ac1c80 <the_index>) at sparse-index.c:404
#1  0x000055555571a979 in do_read_index (istate=istate@entry=0x555555ac1c80 <the_index>, path=path@entry=0x555555ad7b90 ".git/index", must_exist=must_exist@entry=0) at read-cache.c:2386
#2  0x000055555571eb7d in do_read_index (must_exist=0, path=0x555555ad7b90 ".git/index", istate=0x555555ac1c80 <the_index>) at hash.h:244
#3  read_index_from (istate=0x555555ac1c80 <the_index>, path=0x555555ad7b90 ".git/index", gitdir=0x555555ad7b30 ".git") at read-cache.c:2426
#4  0x000055555573f4c2 in repo_read_index (repo=repo@entry=0x555555ac1da0 <the_repo>) at repository.c:286
#5  0x00005555556f14d0 in get_oid_with_context_1 (repo=repo@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", flags=flags@entry=0, prefix=prefix@entry=0x0, 
    oid=oid@entry=0x7fffffffdb00, oc=oc@entry=0x7fffffffda70) at object-name.c:1850
#6  0x00005555556f1f53 in get_oid_with_context (oc=0x7fffffffda70, oid=0x7fffffffdb00, flags=0, str=0x55555582c022 ":.gitmodules", repo=0x555555ac1da0 <the_repo>) at object-name.c:1947
#7  repo_get_oid (r=r@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", oid=oid@entry=0x7fffffffdb00) at object-name.c:1603
#8  0x000055555577330f in config_from_gitmodules (fn=fn@entry=0x555555773460 <gitmodules_fetch_config>, repo=0x555555ac1da0 <the_repo>, data=data@entry=0x7fffffffdb60) at submodule-config.c:650
#9  0x000055555577462d in config_from_gitmodules (data=0x7fffffffdb60, repo=<optimized out>, fn=0x555555773460 <gitmodules_fetch_config>) at submodule-config.c:638
#10 fetch_config_from_gitmodules (max_children=<optimized out>, recurse_submodules=<optimized out>) at submodule-config.c:800
#11 0x00005555555b9e41 in cmd_fetch (argc=1, argv=0x7fffffffe090, prefix=0x0) at builtin/fetch.c:1999
#12 0x0000555555573ff6 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:528
#13 handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:785
#14 0x000055555557528c in run_argv (argv=0x7fffffffddf0, argcp=0x7fffffffddfc) at git.c:857
#15 cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:993
#16 0x0000555555573ac8 in main (argc=3, argv=0x7fffffffe088) at common-main.c:52
```

The operations these commands use are guarded by items such as `index_name_pos()` and others. Since the `.gitmodules` file is always at root, we would not need to expand, anyway.
derrickstolee added a commit that referenced this pull request Nov 4, 2021
When I was playing around with trace2 data and creating flamegraphs, I tried a `git fetch` call to see how the `git-remote-https` command would show up. What I didn't expect was an `ensure_full_index()` region!

It turns out that `git fetch` and `git pull` need to check the index for a `.gitmodules` file to see if it should recurse into any submodules. Here is the stack trace from a debugger:

```
#0  ensure_full_index (istate=0x555555ac1c80 <the_index>) at sparse-index.c:404
#1  0x000055555571a979 in do_read_index (istate=istate@entry=0x555555ac1c80 <the_index>, path=path@entry=0x555555ad7b90 ".git/index", must_exist=must_exist@entry=0) at read-cache.c:2386
#2  0x000055555571eb7d in do_read_index (must_exist=0, path=0x555555ad7b90 ".git/index", istate=0x555555ac1c80 <the_index>) at hash.h:244
#3  read_index_from (istate=0x555555ac1c80 <the_index>, path=0x555555ad7b90 ".git/index", gitdir=0x555555ad7b30 ".git") at read-cache.c:2426
#4  0x000055555573f4c2 in repo_read_index (repo=repo@entry=0x555555ac1da0 <the_repo>) at repository.c:286
#5  0x00005555556f14d0 in get_oid_with_context_1 (repo=repo@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", flags=flags@entry=0, prefix=prefix@entry=0x0, 
    oid=oid@entry=0x7fffffffdb00, oc=oc@entry=0x7fffffffda70) at object-name.c:1850
#6  0x00005555556f1f53 in get_oid_with_context (oc=0x7fffffffda70, oid=0x7fffffffdb00, flags=0, str=0x55555582c022 ":.gitmodules", repo=0x555555ac1da0 <the_repo>) at object-name.c:1947
#7  repo_get_oid (r=r@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", oid=oid@entry=0x7fffffffdb00) at object-name.c:1603
#8  0x000055555577330f in config_from_gitmodules (fn=fn@entry=0x555555773460 <gitmodules_fetch_config>, repo=0x555555ac1da0 <the_repo>, data=data@entry=0x7fffffffdb60) at submodule-config.c:650
#9  0x000055555577462d in config_from_gitmodules (data=0x7fffffffdb60, repo=<optimized out>, fn=0x555555773460 <gitmodules_fetch_config>) at submodule-config.c:638
#10 fetch_config_from_gitmodules (max_children=<optimized out>, recurse_submodules=<optimized out>) at submodule-config.c:800
#11 0x00005555555b9e41 in cmd_fetch (argc=1, argv=0x7fffffffe090, prefix=0x0) at builtin/fetch.c:1999
#12 0x0000555555573ff6 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:528
#13 handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:785
#14 0x000055555557528c in run_argv (argv=0x7fffffffddf0, argcp=0x7fffffffddfc) at git.c:857
#15 cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:993
#16 0x0000555555573ac8 in main (argc=3, argv=0x7fffffffe088) at common-main.c:52
```

The operations these commands use are guarded by items such as `index_name_pos()` and others. Since the `.gitmodules` file is always at root, we would not need to expand, anyway.
derrickstolee added a commit that referenced this pull request Nov 10, 2021
When I was playing around with trace2 data and creating flamegraphs, I tried a `git fetch` call to see how the `git-remote-https` command would show up. What I didn't expect was an `ensure_full_index()` region!

It turns out that `git fetch` and `git pull` need to check the index for a `.gitmodules` file to see if it should recurse into any submodules. Here is the stack trace from a debugger:

```
#0  ensure_full_index (istate=0x555555ac1c80 <the_index>) at sparse-index.c:404
#1  0x000055555571a979 in do_read_index (istate=istate@entry=0x555555ac1c80 <the_index>, path=path@entry=0x555555ad7b90 ".git/index", must_exist=must_exist@entry=0) at read-cache.c:2386
#2  0x000055555571eb7d in do_read_index (must_exist=0, path=0x555555ad7b90 ".git/index", istate=0x555555ac1c80 <the_index>) at hash.h:244
#3  read_index_from (istate=0x555555ac1c80 <the_index>, path=0x555555ad7b90 ".git/index", gitdir=0x555555ad7b30 ".git") at read-cache.c:2426
#4  0x000055555573f4c2 in repo_read_index (repo=repo@entry=0x555555ac1da0 <the_repo>) at repository.c:286
#5  0x00005555556f14d0 in get_oid_with_context_1 (repo=repo@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", flags=flags@entry=0, prefix=prefix@entry=0x0, 
    oid=oid@entry=0x7fffffffdb00, oc=oc@entry=0x7fffffffda70) at object-name.c:1850
#6  0x00005555556f1f53 in get_oid_with_context (oc=0x7fffffffda70, oid=0x7fffffffdb00, flags=0, str=0x55555582c022 ":.gitmodules", repo=0x555555ac1da0 <the_repo>) at object-name.c:1947
#7  repo_get_oid (r=r@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", oid=oid@entry=0x7fffffffdb00) at object-name.c:1603
#8  0x000055555577330f in config_from_gitmodules (fn=fn@entry=0x555555773460 <gitmodules_fetch_config>, repo=0x555555ac1da0 <the_repo>, data=data@entry=0x7fffffffdb60) at submodule-config.c:650
#9  0x000055555577462d in config_from_gitmodules (data=0x7fffffffdb60, repo=<optimized out>, fn=0x555555773460 <gitmodules_fetch_config>) at submodule-config.c:638
#10 fetch_config_from_gitmodules (max_children=<optimized out>, recurse_submodules=<optimized out>) at submodule-config.c:800
#11 0x00005555555b9e41 in cmd_fetch (argc=1, argv=0x7fffffffe090, prefix=0x0) at builtin/fetch.c:1999
#12 0x0000555555573ff6 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:528
#13 handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:785
#14 0x000055555557528c in run_argv (argv=0x7fffffffddf0, argcp=0x7fffffffddfc) at git.c:857
#15 cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:993
#16 0x0000555555573ac8 in main (argc=3, argv=0x7fffffffe088) at common-main.c:52
```

The operations these commands use are guarded by items such as `index_name_pos()` and others. Since the `.gitmodules` file is always at root, we would not need to expand, anyway.
derrickstolee added a commit that referenced this pull request Nov 15, 2021
When I was playing around with trace2 data and creating flamegraphs, I tried a `git fetch` call to see how the `git-remote-https` command would show up. What I didn't expect was an `ensure_full_index()` region!

It turns out that `git fetch` and `git pull` need to check the index for a `.gitmodules` file to see if it should recurse into any submodules. Here is the stack trace from a debugger:

```
#0  ensure_full_index (istate=0x555555ac1c80 <the_index>) at sparse-index.c:404
#1  0x000055555571a979 in do_read_index (istate=istate@entry=0x555555ac1c80 <the_index>, path=path@entry=0x555555ad7b90 ".git/index", must_exist=must_exist@entry=0) at read-cache.c:2386
#2  0x000055555571eb7d in do_read_index (must_exist=0, path=0x555555ad7b90 ".git/index", istate=0x555555ac1c80 <the_index>) at hash.h:244
#3  read_index_from (istate=0x555555ac1c80 <the_index>, path=0x555555ad7b90 ".git/index", gitdir=0x555555ad7b30 ".git") at read-cache.c:2426
#4  0x000055555573f4c2 in repo_read_index (repo=repo@entry=0x555555ac1da0 <the_repo>) at repository.c:286
#5  0x00005555556f14d0 in get_oid_with_context_1 (repo=repo@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", flags=flags@entry=0, prefix=prefix@entry=0x0, 
    oid=oid@entry=0x7fffffffdb00, oc=oc@entry=0x7fffffffda70) at object-name.c:1850
#6  0x00005555556f1f53 in get_oid_with_context (oc=0x7fffffffda70, oid=0x7fffffffdb00, flags=0, str=0x55555582c022 ":.gitmodules", repo=0x555555ac1da0 <the_repo>) at object-name.c:1947
#7  repo_get_oid (r=r@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", oid=oid@entry=0x7fffffffdb00) at object-name.c:1603
#8  0x000055555577330f in config_from_gitmodules (fn=fn@entry=0x555555773460 <gitmodules_fetch_config>, repo=0x555555ac1da0 <the_repo>, data=data@entry=0x7fffffffdb60) at submodule-config.c:650
#9  0x000055555577462d in config_from_gitmodules (data=0x7fffffffdb60, repo=<optimized out>, fn=0x555555773460 <gitmodules_fetch_config>) at submodule-config.c:638
#10 fetch_config_from_gitmodules (max_children=<optimized out>, recurse_submodules=<optimized out>) at submodule-config.c:800
#11 0x00005555555b9e41 in cmd_fetch (argc=1, argv=0x7fffffffe090, prefix=0x0) at builtin/fetch.c:1999
#12 0x0000555555573ff6 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:528
#13 handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:785
#14 0x000055555557528c in run_argv (argv=0x7fffffffddf0, argcp=0x7fffffffddfc) at git.c:857
#15 cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:993
#16 0x0000555555573ac8 in main (argc=3, argv=0x7fffffffe088) at common-main.c:52
```

The operations these commands use are guarded by items such as `index_name_pos()` and others. Since the `.gitmodules` file is always at root, we would not need to expand, anyway.
ldennington pushed a commit to ldennington/git that referenced this pull request Jan 19, 2022
When I was playing around with trace2 data and creating flamegraphs, I tried a `git fetch` call to see how the `git-remote-https` command would show up. What I didn't expect was an `ensure_full_index()` region!

It turns out that `git fetch` and `git pull` need to check the index for a `.gitmodules` file to see if it should recurse into any submodules. Here is the stack trace from a debugger:

```
#0  ensure_full_index (istate=0x555555ac1c80 <the_index>) at sparse-index.c:404
microsoft#1  0x000055555571a979 in do_read_index (istate=istate@entry=0x555555ac1c80 <the_index>, path=path@entry=0x555555ad7b90 ".git/index", must_exist=must_exist@entry=0) at read-cache.c:2386
microsoft#2  0x000055555571eb7d in do_read_index (must_exist=0, path=0x555555ad7b90 ".git/index", istate=0x555555ac1c80 <the_index>) at hash.h:244
microsoft#3  read_index_from (istate=0x555555ac1c80 <the_index>, path=0x555555ad7b90 ".git/index", gitdir=0x555555ad7b30 ".git") at read-cache.c:2426
microsoft#4  0x000055555573f4c2 in repo_read_index (repo=repo@entry=0x555555ac1da0 <the_repo>) at repository.c:286
microsoft#5  0x00005555556f14d0 in get_oid_with_context_1 (repo=repo@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", flags=flags@entry=0, prefix=prefix@entry=0x0, 
    oid=oid@entry=0x7fffffffdb00, oc=oc@entry=0x7fffffffda70) at object-name.c:1850
microsoft#6  0x00005555556f1f53 in get_oid_with_context (oc=0x7fffffffda70, oid=0x7fffffffdb00, flags=0, str=0x55555582c022 ":.gitmodules", repo=0x555555ac1da0 <the_repo>) at object-name.c:1947
microsoft#7  repo_get_oid (r=r@entry=0x555555ac1da0 <the_repo>, name=name@entry=0x55555582c022 ":.gitmodules", oid=oid@entry=0x7fffffffdb00) at object-name.c:1603
microsoft#8  0x000055555577330f in config_from_gitmodules (fn=fn@entry=0x555555773460 <gitmodules_fetch_config>, repo=0x555555ac1da0 <the_repo>, data=data@entry=0x7fffffffdb60) at submodule-config.c:650
microsoft#9  0x000055555577462d in config_from_gitmodules (data=0x7fffffffdb60, repo=<optimized out>, fn=0x555555773460 <gitmodules_fetch_config>) at submodule-config.c:638
microsoft#10 fetch_config_from_gitmodules (max_children=<optimized out>, recurse_submodules=<optimized out>) at submodule-config.c:800
microsoft#11 0x00005555555b9e41 in cmd_fetch (argc=1, argv=0x7fffffffe090, prefix=0x0) at builtin/fetch.c:1999
microsoft#12 0x0000555555573ff6 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:528
microsoft#13 handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:785
microsoft#14 0x000055555557528c in run_argv (argv=0x7fffffffddf0, argcp=0x7fffffffddfc) at git.c:857
microsoft#15 cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:993
microsoft#16 0x0000555555573ac8 in main (argc=3, argv=0x7fffffffe088) at common-main.c:52
```

The operations these commands use are guarded by items such as `index_name_pos()` and others. Since the `.gitmodules` file is always at root, we would not need to expand, anyway.
ldennington pushed a commit to ldennington/git that referenced this pull request Jan 20, 2022
When fetching packfiles, we write a bunch of lockfiles for the packfiles
we're writing into the repository. In order to not leave behind any
cruft in case we exit or receive a signal, we register both an exit
handler as well as signal handlers for common signals like SIGINT. These
handlers will then unlink the locks and free the data structure tracking
them. We have observed a deadlock in this logic though:

    (gdb) bt
    #0  __lll_lock_wait_private () at ../sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:95
    microsoft#1  0x00007f4932bea2cd in _int_free (av=0x7f4932f2eb20 <main_arena>, p=0x3e3e4200, have_lock=0) at malloc.c:3969
    microsoft#2  0x00007f4932bee58c in __GI___libc_free (mem=<optimized out>) at malloc.c:2975
    microsoft#3  0x0000000000662ab1 in string_list_clear ()
    microsoft#4  0x000000000044f5bc in unlock_pack_on_signal ()
    microsoft#5  <signal handler called>
    microsoft#6  _int_free (av=0x7f4932f2eb20 <main_arena>, p=<optimized out>, have_lock=0) at malloc.c:4024
    microsoft#7  0x00007f4932bee58c in __GI___libc_free (mem=<optimized out>) at malloc.c:2975
    microsoft#8  0x000000000065afd5 in strbuf_release ()
    microsoft#9  0x000000000066ddb9 in delete_tempfile ()
    microsoft#10 0x0000000000610d0b in files_transaction_cleanup.isra ()
    microsoft#11 0x0000000000611718 in files_transaction_abort ()
    microsoft#12 0x000000000060d2ef in ref_transaction_abort ()
    microsoft#13 0x000000000060d441 in ref_transaction_prepare ()
    microsoft#14 0x000000000060e0b5 in ref_transaction_commit ()
    microsoft#15 0x00000000004511c2 in fetch_and_consume_refs ()
    microsoft#16 0x000000000045279a in cmd_fetch ()
    microsoft#17 0x0000000000407c48 in handle_builtin ()
    microsoft#18 0x0000000000408df2 in cmd_main ()
    microsoft#19 0x00000000004078b5 in main ()

The process was killed with a signal, which caused the signal handler to
kick in and try free the data structures after we have unlinked the
locks. It then deadlocks while calling free(3P).

The root cause of this is that it is not allowed to call certain
functions in async-signal handlers, as specified by signal-safety(7).
Next to most I/O functions, this list of disallowed functions also
includes memory-handling functions like malloc(3P) and free(3P) because
they may not be reentrant. As a result, if we execute such functions in
the signal handler, then they may operate on inconistent state and fail
in unexpected ways.

Fix this bug by not calling non-async-signal-safe functions when running
in the signal handler. We're about to re-raise the signal anyway and
will thus exit, so it's not much of a problem to keep the string list of
lockfiles untouched. Note that it's fine though to call unlink(2), so
we'll still clean up the lockfiles correctly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Reviewed-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
dscho added a commit that referenced this pull request Nov 5, 2023
The `linux-leaks` job has become a lot more aggressive, failing the
following test cases:

- t0001.52 extensions.objectFormat is not allowed with repo version 0
- t1302.3 gitdir selection on unsupported repo
- t1302.4 gitdir not required mode
- t1302.5 gitdir required mode
- t1302.9 abort version=1 no-such-extension
- t1302.12 abort version=0 noop-v1

The reason is that the `commondir` strbuf _is_ sometimes initialized
_even if_ `discover_git_directory()` fails. The symptom:

    Direct leak of 24 byte(s) in 1 object(s) allocated from:
        #0 0x7f2e80ed8293 in __interceptor_realloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:98
        #1 0x5603ff6ae674 in xrealloc wrapper.c:138
        #2 0x5603ff661801 in strbuf_grow strbuf.c:101
        #3 0x5603ff662417 in strbuf_add strbuf.c:300
        #4 0x5603ff653e2b in strbuf_addstr strbuf.h:310
        #5 0x5603ff65703b in setup_git_directory_gently_1 setup.c:1329
        #6 0x5603ff65731b in discover_git_directory_reason setup.c:1388
        #7 0x5603ff55b6c0 in discover_git_directory setup.h:79
        #8 0x5603ff55b7ce in hook_path_early hook.c:35
        #9 0x5603ff55b97d in find_hook hook.c:77
        #10 0x5603ff55bcd3 in run_hooks_opt hook.c:189
        #11 0x5603ff37ca05 in run_pre_command_hook git.c:457
        #12 0x5603ff37ce0a in run_builtin git.c:532
        #13 0x5603ff37d37e in handle_builtin git.c:798
        #14 0x5603ff37d65a in run_argv git.c:867
        #15 0x5603ff37dc8e in cmd_main git.c:1007
        #16 0x5603ff48f4ee in main common-main.c:62
        #17 0x7f2e80cabd8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58

The fix is easy: always release the `strbuf`s, even when the discovery
of the Git directory failed.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
dscho added a commit that referenced this pull request Oct 9, 2024
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Oct 9, 2024
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
mjcheetham pushed a commit that referenced this pull request Dec 3, 2024
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Dec 17, 2024
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Dec 18, 2024
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Dec 18, 2024
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Dec 19, 2024
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Jan 1, 2025
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Jan 1, 2025
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Jan 1, 2025
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Jan 1, 2025
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Jan 1, 2025
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
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