Thread: Segmentation fault on PG 8.4 CVS head

Segmentation fault on PG 8.4 CVS head

From

"Rushabh Lathia"

Date:

08 January 2009, 09:23:27

Hi All,

While running test with bind varible getting segmentation fault. ( CVS Head 8.4)

For testcase, please find the crash.c (C test) and test.java ( JDBC test) attached with the mail.

Had a quick look at the core dump and found the call stack for the segmentation fault.

(gdb) bt
#0 0x0813768d in analyze_requires_snapshot (parseTree=0x0) at analyze.c:270
#1 0x082e77a8 in exec_bind_message (input_message=0xbfd7d73c) at postgres.c:1698
#2 0x082ec524 in PostgresMain (argc=4, argv=0x916fc70, username=0x916fb7c "rushabh") at postgres.c:4882
#3 0x082ac10a in BackendRun (port=0x9191b18) at postmaster.c:3309
#4 0x082ab4d4 in BackendStartup (port=0x9191b18) at postmaster.c:2881
#5 0x082a8ae1 in ServerLoop () at postmaster.c:1291

Had a look at the previous version and found that because of following condition added with the new PG merge into exec_bind_message(); we end up with the segmentation fault.

exec_bind_message{
...
   /*
    * Set a snapshot if we have parameters to fetch (since the input
    * functions might need it) or the query isn't a utility command (and
    * hence could require redoing parse analysis and planning).
    */
   if (numParams > 0 || analyze_requires_snapshot(psrc->raw_parse_tree))
   {
       PushActiveSnapshot(GetTransactionSnapshot());
       snapshot_set = true;
   }
...
}

Condition added with "Fix failure to ensure that a snapshot is available to datatype input functions" commit. (http://git.postgresql.org/?p=postgresql.git;a=commitdiff;h=d5e7e5dd7c81440bb46f52872906633ee2b388c1)

Not very much sure but for the quick check I just modifiled condition by added check for raw_parse_tree and test worked file.

Modified condition:
   /*
    * Set a snapshot if we have parameters to fetch (since the input
    * functions might need it) or the query isn't a utility command (and
    * hence could require redoing parse analysis and planning).
    */
   if (numParams > 0 ||
           (psrc->raw_parse_tree && analyze_requires_snapshot(psrc->raw_parse_tree)))
   {
       PushActiveSnapshot(GetTransactionSnapshot());
       snapshot_set = true;
   }

Another fix would be to add check for parseTree into analyze_requires_snapshot().

Thanks ,
Rushabh Lathia
www.EnterpriseDB.com

Attachment

Re: Segmentation fault on PG 8.4 CVS head

From

Tom Lane

Date:

08 January 2009, 12:44:39

"Rushabh Lathia" <rushabh.lathia@gmail.com> writes:
> While running test with bind varible getting segmentation fault. ( CVS Head
> 8.4)

Fixed, thanks.

>  Another fix would be to add check for  parseTree into
> analyze_requires_snapshot().

This one seems the more bulletproof approach.
        regards, tom lane

Re: Segmentation fault on PG 8.4 CVS head

From

Heikki Linnakangas

Date:

08 January 2009, 15:51:12

Tom fixed this upstream, and I just merged with PostgreSQL CVS HEAD 
again. The buildfarm crash should now be fixed.

Rushabh Lathia wrote:
> Hi All,
> 
> While running test with bind varible getting segmentation fault. ( CVS Head
> 8.4)
> 
> For testcase, please find the crash.c (C test) and test.java ( JDBC test)
> attached with the mail.
> 
> Had a quick look at the core dump and found the call stack for the
> segmentation fault.
> 
> (gdb) bt
> #0  0x0813768d in analyze_requires_snapshot (parseTree=0x0) at analyze.c:270
> 
> #1  0x082e77a8 in exec_bind_message (input_message=0xbfd7d73c) at
> postgres.c:1698
> #2  0x082ec524 in PostgresMain (argc=4, argv=0x916fc70, username=0x916fb7c
> "rushabh") at postgres.c:4882
> #3  0x082ac10a in BackendRun (port=0x9191b18) at postmaster.c:3309
> #4  0x082ab4d4 in BackendStartup (port=0x9191b18) at postmaster.c:2881
> #5  0x082a8ae1 in ServerLoop () at postmaster.c:1291
> 
> Had a look at the previous version and found that because of following
> condition added with the new PG merge into exec_bind_message(); we end up
> with the segmentation fault.
> 
> exec_bind_message{
> ...
>    /*
>     * Set a snapshot if we have parameters to fetch (since the input
>     * functions might need it) or the query isn't a utility command (and
>     * hence could require redoing parse analysis and planning).
>     */
>    if (numParams > 0 || analyze_requires_snapshot(psrc->raw_parse_tree))
>    {
>        PushActiveSnapshot(GetTransactionSnapshot());
>        snapshot_set = true;
>    }
> ...
> }
> 
> 
> Condition added with "Fix failure to ensure that a snapshot is available to
> datatype input functions" commit. (
> http://git.postgresql.org/?p=postgresql.git;a=commitdiff;h=d5e7e5dd7c81440bb46f52872906633ee2b388c1
> )
> 
> Not very much sure but for the quick check I just modifiled condition by
> added check for raw_parse_tree and test worked file.
> 
> Modified condition:
>    /*
>     * Set a snapshot if we have parameters to fetch (since the input
>     * functions might need it) or the query isn't a utility command (and
>     * hence could require redoing parse analysis and planning).
>     */
>    if (numParams > 0 ||
>            (psrc->raw_parse_tree &&
> analyze_requires_snapshot(psrc->raw_parse_tree)))
>    {
>        PushActiveSnapshot(GetTransactionSnapshot());
>        snapshot_set = true;
>    }
> 
>  Another fix would be to add check for  parseTree into
> analyze_requires_snapshot().
> 
> Thanks ,
> Rushabh Lathia
> www.EnterpriseDB.com
> 
> 
> 
> ------------------------------------------------------------------------
> 
> 


--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com

Re: Segmentation fault on PG 8.4 CVS head

From

Heikki Linnakangas

Date:

08 January 2009, 15:54:06

Sorry for the noise, I didn't mean to sent this to the mailing list..

(the context is that this bug was found by a test case in EnterpriseDB 
JDBC buildfarm)

Heikki Linnakangas wrote:
> Tom fixed this upstream, and I just merged with PostgreSQL CVS HEAD 
> again. The buildfarm crash should now be fixed.
> 
> Rushabh Lathia wrote:
>> Hi All,
>>
>> While running test with bind varible getting segmentation fault. ( CVS 
>> Head
>> 8.4)
>>
>> For testcase, please find the crash.c (C test) and test.java ( JDBC test)
>> attached with the mail.
>>
>> Had a quick look at the core dump and found the call stack for the
>> segmentation fault.
>>
>> (gdb) bt
>> #0  0x0813768d in analyze_requires_snapshot (parseTree=0x0) at 
>> analyze.c:270
>>
>> #1  0x082e77a8 in exec_bind_message (input_message=0xbfd7d73c) at
>> postgres.c:1698
>> #2  0x082ec524 in PostgresMain (argc=4, argv=0x916fc70, 
>> username=0x916fb7c
>> "rushabh") at postgres.c:4882
>> #3  0x082ac10a in BackendRun (port=0x9191b18) at postmaster.c:3309
>> #4  0x082ab4d4 in BackendStartup (port=0x9191b18) at postmaster.c:2881
>> #5  0x082a8ae1 in ServerLoop () at postmaster.c:1291
>>
>> Had a look at the previous version and found that because of following
>> condition added with the new PG merge into exec_bind_message(); we end up
>> with the segmentation fault.
>>
>> exec_bind_message{
>> ...
>>    /*
>>     * Set a snapshot if we have parameters to fetch (since the input
>>     * functions might need it) or the query isn't a utility command (and
>>     * hence could require redoing parse analysis and planning).
>>     */
>>    if (numParams > 0 || analyze_requires_snapshot(psrc->raw_parse_tree))
>>    {
>>        PushActiveSnapshot(GetTransactionSnapshot());
>>        snapshot_set = true;
>>    }
>> ...
>> }
>>
>>
>> Condition added with "Fix failure to ensure that a snapshot is 
>> available to
>> datatype input functions" commit. (
>> http://git.postgresql.org/?p=postgresql.git;a=commitdiff;h=d5e7e5dd7c81440bb46f52872906633ee2b388c1 
>>
>> )
>>
>> Not very much sure but for the quick check I just modifiled condition by
>> added check for raw_parse_tree and test worked file.
>>
>> Modified condition:
>>    /*
>>     * Set a snapshot if we have parameters to fetch (since the input
>>     * functions might need it) or the query isn't a utility command (and
>>     * hence could require redoing parse analysis and planning).
>>     */
>>    if (numParams > 0 ||
>>            (psrc->raw_parse_tree &&
>> analyze_requires_snapshot(psrc->raw_parse_tree)))
>>    {
>>        PushActiveSnapshot(GetTransactionSnapshot());
>>        snapshot_set = true;
>>    }
>>
>>  Another fix would be to add check for  parseTree into
>> analyze_requires_snapshot().
>>
>> Thanks ,
>> Rushabh Lathia
>> www.EnterpriseDB.com
>>
>>
>>
>> ------------------------------------------------------------------------
>>
>>
> 
> 


--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com