ExecAppendAsyncEventWait() in REL_14_STABLE can corrupt PG_exception_stack

Alexander Pyhalov <a.pyhalov@postgrespro.ru>

From: Alexander Pyhalov <a.pyhalov@postgrespro.ru>

To: Pgsql Hackers <pgsql-hackers@postgresql.org>

Date: 2024-02-23T10:21:14Z

Lists: pgsql-hackers

Attachments

0001-Avoid-corrupting-PG_exception_stack-in-ExecAppendAsy.patch (text/x-diff) patch 0001

Hi.

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.

The following patch heals the issue.

-- l
Best regards,
Alexander Pyhalov,
Postgres Professional

Commits

Fix bogus coding in ExecAppendAsyncEventWait().
- e10ca95ff7db 14.12 landed
- 3f96d113ff84 15.7 landed
- f6f61a4bd9cc 16.3 landed
Fix resource leak when a FDW's ForeignAsyncRequest function fails
- 555276f85940 14.11 cited
postgres_fdw: Fix handling of pending asynchronous requests.
- 1ec7fca85921 15.0 cited
Add support for asynchronous execution.
- 27e1f14563cf 14.0 cited