Re: Segmentation fault on PG 8.4 CVS head

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