Horton

Re: Missing error_context_stack = NULL in AutoVacWorkerMain()

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
Cc: Ashwin Agrawal <aagrawal@pivotal.io>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>, Paul Guo <paulguo@gmail.com>
Date: 2019-10-21T05:01:50Z
Lists: pgsql-hackers 
Michael Paquier <michael@paquier.xyz> writes:
> On Mon, Oct 21, 2019 at 12:47:40AM -0400, Tom Lane wrote:
>> This seems like a real and possibly serious bug to me.  Backend sigsetjmp
>> callers *must* clear error_context_stack (or restore it to a previous
>> value), because if it isn't NULL it's surely pointing at garbage, ie a
>> local variable that's no longer part of the valid stack.

> Sure.  From my recollection of memories we never set it in autovacuum
> code paths (including index entry deletions), so I don't think that we
> have an actual live bug here.

Uh ... what about, say, auto-analyze on an expression index?  That
could call user-defined PL functions and thus reach just about all
of the backend.

			regards, tom lane

Commits

  1. Clean up properly error_context_stack in autovacuum worker on exception