Horton

Re: ExecAppendAsyncEventWait() in REL_14_STABLE can corrupt PG_exception_stack

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Alexander Pyhalov <a.pyhalov@postgrespro.ru>
Cc: Pgsql Hackers <pgsql-hackers@postgresql.org>
Date: 2024-02-24T01:06:29Z
Lists: pgsql-hackers 
On Fri, Feb 23, 2024 at 01:21:14PM +0300, Alexander Pyhalov wrote:
> Recent commit 555276f8594087ba15e0d58e38cd2186b9f39f6d introduced final
> cleanup of node->as_eventset in ExecAppendAsyncEventWait().
> Unfortunately, now this function can return in the middle of TRY/FINALLY
> block, without restoring PG_exception_stack.
> 
> We found this while working on our FDW. Unfortunately, I couldn't reproduce
> the issue with postgres_fdw, but it seems it is also affected.

Ugh, yes, you are obviously right that the early return is wrong.
I'll look into fixing that where appropriate.  Thanks for the report,
Alexander!
--
Michael

Commits

  1. Fix bogus coding in ExecAppendAsyncEventWait().

  2. Fix resource leak when a FDW's ForeignAsyncRequest function fails

  3. postgres_fdw: Fix handling of pending asynchronous requests.

  4. Add support for asynchronous execution.