Cwd has memcpy source/destination overlap

[khwilliamson]

Module: PathTools::Cwd

Description

Here's some of the errors found by valgrind

../lib/perl5db.t: ==508232== Source and destination overlap in memcpy_chk(0x1ffeffb740, 0x1ffeffb744, 15)
../lib/perl5db.t: ==508232== at 0x48539B2: __memcpy_chk (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
../lib/perl5db.t: ==508232== by 0x568AF8D: XS_Cwd_abs_path (in /home/khw/perl/test_locale4/lib/auto/Cwd/Cwd.so)
../lib/perl5db.t: ==508232== by 0x21E7A6: Perl_pp_entersub (in /home/khw/perl/test_locale4/perl)
../lib/perl5db.t: ==508232== by 0x214865: Perl_runops_standard (in /home/khw/perl/test_locale4/perl)
../lib/perl5db.t: ==508232== by 0x174AAB: perl_run (in /home/khw/perl/test_locale4/perl)
../lib/perl5db.t: ==508232== by 0x14B501: main (in /home/khw/perl/test_locale4/perl)
../lib/perl5db.t: ==508232==
../lib/File/stat.t: ==508581== Source and destination overlap in memcpy_chk(0x1ffeffb740, 0x1ffeffb744, 15)
../lib/File/stat.t: ==508581== at 0x48539B2: __memcpy_chk (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
../lib/File/stat.t: ==508581== by 0x66D1F8D: XS_Cwd_abs_path (in /home/khw/perl/test_locale4/lib/auto/Cwd/Cwd.so)
../lib/File/stat.t: ==508581== by 0x21E7A6: Perl_pp_entersub (in /home/khw/perl/test_locale4/perl)
../lib/File/stat.t: ==508581== by 0x214865: Perl_runops_standard (in /home/khw/perl/test_locale4/perl)
../lib/File/stat.t: ==508581== by 0x174AAB: perl_run (in /home/khw/perl/test_locale4/perl)
../lib/File/stat.t: ==508581== by 0x14B501: main (in /home/khw/perl/test_locale4/perl)
../lib/File/stat.t: ==508581==
op/coreamp.t: ==514663== Source and destination overlap in memcpy_chk(0x1ffeffb750, 0x1ffeffb754, 15)
op/coreamp.t: ==514663== at 0x48539B2: __memcpy_chk (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
op/coreamp.t: ==514663== by 0x5693F8D: XS_Cwd_abs_path (in /home/khw/perl/test_locale4/lib/auto/Cwd/Cwd.so)
op/coreamp.t: ==514663== by 0x21E7A6: Perl_pp_entersub (in /home/khw/perl/test_locale4/perl)
op/coreamp.t: ==514663== by 0x214865: Perl_runops_standard (in /home/khw/perl/test_locale4/perl)
op/coreamp.t: ==514663== by 0x1749BA: perl_run (in /home/khw/perl/test_locale4/perl)
op/coreamp.t: ==514663== by 0x14B501: main (in /home/khw/perl/test_locale4/perl)
op/coreamp.t: ==514663==
../lib/File/Copy.t: ==515806== Source and destination overlap in memcpy_chk(0x1ffeffb740, 0x1ffeffb744, 15)
../lib/File/Copy.t: ==515806== at 0x48539B2: __memcpy_chk (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
../lib/File/Copy.t: ==515806== by 0x66D1F8D: XS_Cwd_abs_path (in /home/khw/perl/test_locale4/lib/auto/Cwd/Cwd.so)
../lib/File/Copy.t: ==515806== by 0x21E7A6: Perl_pp_entersub (in /home/khw/perl/test_locale4/perl)
../lib/File/Copy.t: ==515806== by 0x214865: Perl_runops_standard (in /home/khw/perl/test_locale4/perl)
../lib/File/Copy.t: ==515806== by 0x1749BA: perl_run (in /home/khw/perl/test_locale4/perl)
../lib/File/Copy.t: ==515806== by 0x14B501: main (in /home/khw/perl/test_locale4/perl)
../lib/File/Copy.t: ==515806==

Steps to Reproduce

valgrind ./perl -Ilib t/op/coreamp.t
Expected behavior

No valgrind errors
Perl configuration

# perl -V output goes here

Summary of my perl5 (revision 5 version 37 subversion 2) configuration:
Local Commit: 2be99e554d28284bf689eb425cc18cc2ff26c037
Ancestor: 4fa31e7
Platform:
osname=linux
osvers=5.15.0-41-generic
archname=x86_64-linux-thread-multi
uname='linux khw8950 5.15.0-41-generic #44-ubuntu smp wed jun 22 14:20:53 utc 2022 x86_64 x86_64 x86_64 gnulinux '
config_args='-des -Uversiononly -Dprefix=/home/khw/devel -Dusedevel -Doptimize=-O0 -DDEBUGGING -A'optimize=-ggdb3' -Accflags='-Wno-deprecated' -Dman1dir='none' -Dman3dir='none' -Dcc=g++ -Dusecbacktrace -Dusethreads'
hint=recommended
useposix=true
d_sigaction=define
useithreads=define
usemultiplicity=define
use64bitint=define
use64bitall=define
uselongdouble=undef
usemymalloc=n
default_inc_excludes_dot=define
Compiler:
cc='g++'
ccflags ='-D_REENTRANT -D_GNU_SOURCE -Wno-deprecated -fwrapv -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
optimize='-O0 -ggdb3'
cppflags='-D_REENTRANT -D_GNU_SOURCE -Wno-deprecated -fwrapv -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
ccversion=''
gccversion='10.3.0'
gccosandvers=''
intsize=4
longsize=8
ptrsize=8
doublesize=8
byteorder=12345678
doublekind=3
d_longlong=define
longlongsize=8
d_longdbl=define
longdblsize=16
longdblkind=3
ivtype='long'
ivsize=8
nvtype='double'
nvsize=8
Off_t='off_t'
lseeksize=8
alignbytes=8
prototype=define
Linker and Libraries:
ld='g++'
ldflags =' -fstack-protector-strong -L/usr/local/lib'
libpth=/usr/local/lib /usr/lib/x86_64-linux-gnu /usr/lib /usr/lib64
libs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
libc=/lib/x86_64-linux-gnu/libc.so.6
so=so
useshrplib=false
libperl=libperl.a
gnulibc_version='2.35'
Dynamic Linking:
dlsrc=dl_dlopen.xs
dlext=so
d_dlsymun=undef
ccdlflags='-Wl,-E'
cccdlflags='-fPIC'
lddlflags='-shared -O0 -ggdb3 -L/usr/local/lib -fstack-protector-strong'

Characteristics of this binary (from libperl):
Compile-time options:
DEBUGGING
HAS_TIMES
MULTIPLICITY
PERLIO_LAYERS
PERL_COPY_ON_WRITE
PERL_DONT_CREATE_GVSV
PERL_MALLOC_WRAP
PERL_OP_PARENT
PERL_PRESERVE_IVUV
PERL_TRACK_MEMPOOL
PERL_USE_DEVEL
PERL_USE_SAFE_PUTENV
USE_64_BIT_ALL
USE_64_BIT_INT
USE_ITHREADS
USE_LARGE_FILES
USE_LOCALE
USE_LOCALE_COLLATE
USE_LOCALE_CTYPE
USE_LOCALE_NUMERIC
USE_LOCALE_TIME
USE_PERLIO
USE_PERL_ATOF
USE_REENTRANT_API
USE_THREAD_SAFE_LOCALE
Locally applied patches:
2252a32df71dc72ed923004829b9685176d51884
4ab9398ad210bfcc762c25ef07db9562a9a478ea
Built under linux
Compiled at Jul 13 2022 09:14:12
%ENV:
PERL5OPT="-w"
PERL_DIFF_TOOL="wgdiff"
PERL_POD_PEDANTIC="1"
PERL_TEST_HARNESS_ASAP="1"
@inc:
lib
/home/khw/devel/lib/perl5/site_perl/5.37.2/x86_64-linux-thread-multi
/home/khw/devel/lib/perl5/site_perl/5.37.2
/home/khw/devel/lib/perl5/5.37.2/x86_64-linux-thread-multi
/home/khw/devel/lib/perl5/5.37.2
/home/khw/devel/lib/perl5/site_perl/5.33.3
/home/khw/devel/lib/perl5/site_perl/5.33.2
/home/khw/devel/lib/perl5/site_perl/5.31.7
/home/khw/devel/lib/perl5/site_perl/5.31.4
/home/khw/devel/lib/perl5/site_perl/5.31.3
/home/khw/devel/lib/perl5/site_perl/5.31.2
/home/khw/devel/lib/perl5/site_perl/5.31.1
/home/khw/devel/lib/perl5/site_perl/5.29.10
/home/khw/devel/lib/perl5/site_perl/5.29.8
/home/khw/devel/lib/perl5/site_perl/5.29.7
/home/khw/devel/lib/perl5/site_perl/5.28.0
/home/khw/devel/lib/perl5/site_perl/5.26.0
/home/khw/devel/lib/perl5/site_perl/5.6.2
/home/khw/devel/lib/perl5/site_perl

[tonycoz]

I can't reproduce this.

The lack of line numbers in the report is puzzling, it might be that valgrind can't handle -ggdb3 debug info.

[jkeenan]

I can't reproduce this.

The lack of line numbers in the report is puzzling, it might be that valgrind can't handle -ggdb3 debug info.

@khwilliamson, what should be our next steps with this problem?

[khwilliamson]

It is no longer happening for me.

[tonycoz]

I managed to produce a very similar error here:

==2223460== Source and destination overlap in memcpy_chk(0x1ffeff3b60, 0x1ffeff3b65, 64)
==2223460==    at 0x48408F0: __memcpy_chk (vg_replace_strmem.c:1593)
==2223460==    by 0x4849A3B: memmove (string_fortified.h:40)
==2223460==    by 0x4849A3B: bsd_realpath (Cwd.xs:144)
==2223460==    by 0x484B22F: XS_Cwd_abs_path (Cwd.xs:614)
==2223460==    by 0x29B272: Perl_pp_entersub (pp_hot.c:5457)
==2223460==    by 0x249D4C: Perl_runops_debug (dump.c:2730)
==2223460==    by 0x17CEDC: Perl_call_sv (perl.c:3117)
==2223460==    by 0x180FB7: Perl_call_list (perl.c:5188)
==2223460==    by 0x16F321: S_process_special_blocks (op.c:10844)
==2223460==    by 0x1724F8: Perl_newATTRSUB_x (op.c:10684)
==2223460==    by 0x174DCB: Perl_utilize (op.c:7617)
==2223460==    by 0x1DA0B9: Perl_yyparse (perly.y:395)
==2223460==    by 0x312907: S_doeval_compile (pp_ctl.c:3729)
==2223460== 

but the line mentioned in Cwd.xs is a call to memmove() (which allows for overlap).

This may be a valgrind bug, or a bad interaction between glibc and valgrind, see https://bugs.kde.org/show_bug.cgi?id=453084