Feedback-ID: ie3de48e3:Fastmail
Date: Tue, 26 May 2026 13:09:13 +0200
From: Alvaro Herrera <alvherre@kurilemu.de>
To: Michael Paquier <michael@paquier.xyz>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, euler@eulerto.com,
	pgsql-hackers@lists.postgresql.org
Subject: Re: NULL pointer dereference in syslogger with load_libraries() and
 -DEXEC_BACKEND at startup
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On 2026-May-26, Michael Paquier wrote:

> This issue is different, it is a Postgres logic bug, so adding an
> exception like the one you are suggesting is just a shortcut hiding
> the real issue: the log file is not ready yet, but the syslogger is
> invoked at a point when it thinks the log file exists.

I think we can solve this easily by flipping a new Boolean value at the
same point were MyBackendType was previously set.  The attached POC
fixes the scenario you described; can you confirm?  It needs some
additional comments, of course.

(There is one more place in elog.c where we check that MyBackendType is
_not_ B_LOGGER, but I think that one is correct as-is; and I'm wondering
if that would behave correctly before 0c8e082fba8d.)

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
“Cuando no hay humildad las personas se degradan” (A. Christie)

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