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help / color / mirror / Atom feedFrom: Michael Paquier <michael@paquier.xyz>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Make GetSnapshotData() more resilient on out-of-memory errors
Date: Thu, 18 Jun 2026 05:14:16 +0000
Message-ID: <E1wa54y-000p5X-0o@gemulon.postgresql.org> (raw)
Make GetSnapshotData() more resilient on out-of-memory errors
If the allocation of Snapshot->subxip fails, a follow-up call of
GetSnapshotData() would see a partially-initialized snapshot, causing a
NULL dereference on reentry when using "subxip" because only "xip" would
be allocated. In the event of an out-of-memory error when allocating
"subxip", "xip" is now reset before throwing an ERROR, so as Snapshots
can be allocated and handled gracefully on retry.
This problem is unlikely going to show up in practice, so no backpatch.
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Discussion: https://postgr.es/m/e77acaac-a1b3-40b3-99ee-5769b4e453e4@gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/29fb598b9cad898ef851b9a7704f980218057562
Modified Files
--------------
src/backend/storage/ipc/procarray.c | 8 ++++++++
1 file changed, 8 insertions(+)
Message-ID: <E1wa54y-000p5X-0o@gemulon.postgresql.org>
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To: pgsql-committers@postgresql.org
Cc: michael@paquier.xyz, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Make GetSnapshotData() more resilient on out-of-memory errors
In-Reply-To: <E1wa54y-000p5X-0o@gemulon.postgresql.org>
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