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server: fix COM_FIELD_LIST response bug that make mariadb-client crash during use db #6918

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merged 6 commits into from
Jun 28, 2018
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server: fix COM_FIELD_LIST response bug that make mariadb-client crash during use db #6918

merged 6 commits into from
Jun 28, 2018

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lysu
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@lysu lysu commented Jun 27, 2018 •
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What have you changed? (mandatory)

column-definitions in COM_FIELD_LIST response need write addition default-values part even though we omit default-values.

and some client like MariaDB-cli(without -A)'s use db will trigger COM_FEILD_LIST and read default-values length bit in response, it will meet fault if we haven't give it.
https://github.com/MariaDB/server/blob/72b6d01848e56a75349d663bc61bbe71f97a280b/sql-common/client.c#L1519

  • dump() add option parameter and pass WithDefaultValues option in handle_field_list()
  • check option and add default values length bit in dump
  • remove unuse DefaultValue DefaultValueLength field from server.ColumnInfo

fix #6622

What are the type of the changes (mandatory)?

The currently defined types are listed below, please pick one of the types for this PR by removing the others:

  • Bug fix (non-breaking change which fixes an issue)

How has this PR been tested (mandatory)?

  • manual tests

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@lysu lysu changed the title server: fix COM_FIELD_LIST response. server: fix COM_FIELD_LIST response bug that make mariadb-client coredump crash Jun 27, 2018
@lysu lysu changed the title server: fix COM_FIELD_LIST response bug that make mariadb-client coredump crash server: fix COM_FIELD_LIST response bug that make mariadb-client crash during use db Jun 27, 2018
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shenli commented Jun 27, 2018

Well done!

shenli
shenli reviewed Jun 27, 2018
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server/column.go Outdated
// Dump dumps ColumnInfo to bytes.
func (column *ColumnInfo) Dump(buffer []byte) []byte {
func (column *ColumnInfo) Dump(buffer []byte, flags DumpOpt) []byte {
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Can we use a bool argument to control whether output default value?

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done~

zz-jason
zz-jason reviewed Jun 27, 2018
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server/column.go Outdated
if flags&WithDefaultValue > 0 {
// Current we doesn't output defaultValue but reserve defaultValue length bit to make mariadb client happy.
// https://dev.mysql.com/doc/internals/en/com-query-response.html#column-definition
buffer = dumpUint64(buffer, 0)
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why this change works?

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@lysu lysu Jun 27, 2018 •
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because in protocol definition https://dev.mysql.com/doc/internals/en/com-query-response.html#column-definition said.

  if command was COM_FIELD_LIST {
lenenc_int     length of default-values
string[$len]   default values
  }

So, if it's a response of COM_FIELD_LIST, we should actually add default values part use just like this.

+----------------------+-------------------+------------+--------------+--------------+-----------+--------------------+
|                      |                   |            |              |              |           |                    |
|                      |                   |            |              |              |           |                    |
|                      |                   |            |              |              |           |                    |
|                      |                   |            |              |              |           |                    |
|      ....sth we      |  length byte of   |   default  |   default    |   default    |  default  |   ..............   |
|      outputed        |  default values   |   value 1  |   value 2    |   value 3    |  value 4  |                    |
|                      |                   |            |              |              |           |                    |
|                      |                   |            |              |              |           |                    |
|                      |                   |            |              |              |           |                    |
+----------------------+-------------------+------------+--------------+--------------+-----------+--------------------+

but In tidb we omit default values(It seems not easy to output that....), and omit all default values bytes...but mariadb will read length byte of default values without condition, after send COM_FIELD_LIST. see: https://github.com/MariaDB/server/blob/72b6d01848e56a75349d663bc61bbe71f97a280b/sql-common/client.c#L1519

So at this PR, we don't complete fill all default values but follow the protocol give client an empty default values

+-------------+--------------+
|             |              |
|             |              |
|             |              |
|  sth we     | length byte  |
|  outputed   | of default   |
|             | values       |
|             |              |
|             |    (0)       |
|             |              |
+-------------+--------------+

so mariadb will read length byte without out of index crash.

@lysu lysu requested review from coocood and tiancaiamao June 27, 2018 06:26
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:lgtm:

Review status: 0 of 4 files reviewed, 1 unresolved discussion (waiting on @shenli, @tiancaiamao, and @coocood)

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Review status: 0 of 4 files reviewed, 2 unresolved discussions (waiting on @shenli, @lysu, @tiancaiamao, and @coocood)

server/column.go, line 50 at r3 (raw file):

How about change it like this:

if len(column.DefaultValue) == 0 {
    ...
} else {
    buffer = dumpUint64(buffer, 0)
}

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@zz-jason zz-jason added the status/LGT1 Indicates that a PR has LGTM 1. label Jun 27, 2018
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Reviewed 1 of 4 files at r1, 2 of 3 files at r2, 1 of 1 files at r3.
Review status: all files reviewed, 2 unresolved discussions (waiting on @shenli, @lysu, and @coocood)

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shenli commented Jun 27, 2018

LGTM

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shenli commented Jun 27, 2018

/run-all-tests

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@tiancaiamao PTAL

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lysu commented Jun 27, 2018

@tiancaiamao PTAL

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lysu commented Jun 27, 2018

/run-all-tests

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LGTM @shenli

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shenli commented Jun 27, 2018

LGTM

@shenli shenli added status/LGT2 Indicates that a PR has LGTM 2. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Jun 27, 2018
shenli
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shenli commented Jun 27, 2018

@lysu Could you add some integration test for this?

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lysu commented Jun 28, 2018

/run-mybatis-test

lysu added 5 commits June 28, 2018 11:18
@lysu
server: fix COM_FIELD_LIST response.
37e06d8 
[column-definitions](https://dev.mysql.com/doc/internals/en/com-query-response.html#column-definition) in COM_FIELD_LIST response need write addition default-values part even though we omit default-values.
and some client like MariaDB-cli will read default-values length bit and meet fault if we haven't give it.
https://github.com/MariaDB/server/blob/72b6d01848e56a75349d663bc61bbe71f97a280b/sql-common/client.c#L1519

fix #6622
@lysu
server: fix review comment.
5fe93ae
@lysu
server: fix review comment.
0b6ce2f
@lysu
server: fix review comment.
0547af6 
we should open for continue edition that fill default value.
@lysu
server: fix review comment.
91bccdf
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lysu commented Jun 28, 2018

PTAL @coocood

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LGTM

@jackysp jackysp merged commit ef3d040 into pingcap:master Jun 28, 2018
This was referenced Jun 28, 2018
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coocood pushed a commit that referenced this pull request Jun 28, 2018
@lysu @coocood
server: fix COM_FIELD_LIST response bug that make mariadb-client cras…
56135f4 
…h during `use db` (#6918) (#6929)
@lysu lysu deleted the dev-fix-maria-db-client branch July 8, 2018 07:43
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@coocood coocood Awaiting requested review from coocood

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when loading data， execute “use database” crashed
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