From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Avoid possibly-theoretical OOM crash hazard in hash_create().
Date: Wed, 23 Apr 2025 20:05:17 +0000
Message-ID: <E1u7gLM-001SG0-30@gemulon.postgresql.org> (raw)
Avoid possibly-theoretical OOM crash hazard in hash_create().
One place in hash_create() used DynaHashAlloc() as a convenient
shorthand for MemoryContextAlloc(). That was fine when it was
written, but it stopped being fine when 9c911ec06 changed
DynaHashAlloc() to use MCXT_ALLOC_NO_OOM (mea culpa). Change
the code to call plain MemoryContextAlloc() as intended.
I think that this bug may be unreachable in practice, since we now
always create AllocSets with some space already allocated, so that
an OOM failure here for a non-shared hash table should be impossible
(with a hash table name of reasonable length anyway). And there
aren't enough shared hash tables to make a crash for one of those
probable. Nonetheless it's clearly not operating as designed, so
back-patch to v16 where 9c911ec06 came in.
Reported-by: Maksim Korotkov <m.korotkov@postgrespro.ru>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/219bdccd460510efaccf90b57e5e5ef2@postgrespro.ru
Backpatch-through: 16
Branch
------
REL_16_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/f45bdb13397fc142bc95513783dca3e0106e57af
Modified Files
--------------
src/backend/utils/hash/dynahash.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-committers@postgresql.org
Cc: tgl@sss.pgh.pa.us, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Avoid possibly-theoretical OOM crash hazard in hash_create().
In-Reply-To: <E1u7gLM-001SG0-30@gemulon.postgresql.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox