Feedback-ID: i0fe9450f:Fastmail
Date: Thu, 16 Jul 2026 09:15:18 +0900
From: Michael Paquier <michael@paquier.xyz>
To: =?iso-8859-1?Q?=C1lvaro?= Herrera <alvherre@kurilemu.de>
Cc: Anton Voloshin <a.voloshin@postgrespro.ru>,
	Euler Taveira <euler@eulerto.com>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: NULL pointer dereference in syslogger with load_libraries() and
 -DEXEC_BACKEND at startup
Message-ID: <algiltRh8fHYZD0s@paquier.xyz>
References: <4ccb96f8-0bac-4362-ac22-2f81d1b0062c@postgrespro.ru>
 <alew9Lk3BXiGZsm7@alvherre.pgsql>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="g+dP6SaNHEH9I1Ac"
Content-Disposition: inline
In-Reply-To: <alew9Lk3BXiGZsm7@alvherre.pgsql>
Archived-At: 
 <https://www.postgresql.org/message-id/algiltRh8fHYZD0s%40paquier.xyz>
Precedence: bulk

--g+dP6SaNHEH9I1Ac
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Wed, Jul 15, 2026 at 06:14:30PM +0200, Alvaro Herrera wrote:
> Michael, looking at=20
> https://github.com/michaelpq/pg_plugins/blob/main/jsonlog/jsonlog.c
> do you see an issue with this variable?

I have not directly tested it yet (will perhaps do so later this
week or later), but I am pretty sure that this module is broken as-is
with v19 under EXEC_BACKEND.  Not checking for syslogger_setup_done
and only redirection_done means that the module could try to send some
chunks of data to the syslogger without the file handles being set,
crashing the syslogger the same way as what I have done upthread.

I have created an item to look at that later, for now:
https://github.com/michaelpq/pg_plugins/issues/56

AFAIK, jsonlog is still used in some container setups even with the
in-core option in place since v15, folks have been keeping asking for
it.  I suspect that there is close to zero use of it under
EXEC_BACKEND, but we surely should fix the issue anyway..
--
Michael

--g+dP6SaNHEH9I1Ac
Content-Type: application/pgp-signature; name=signature.asc

-----BEGIN PGP SIGNATURE-----
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=KTdn
-----END PGP SIGNATURE-----

--g+dP6SaNHEH9I1Ac--