Thread: pgsql: Fix memory leak in Incremental Sort rescans

pgsql: Fix memory leak in Incremental Sort rescans

From
Tomas Vondra
Date:
Fix memory leak in Incremental Sort rescans

The Incremental Sort had a couple issues, resulting in leaking memory
during rescans, possibly triggering OOM. The code had a couple of
related flaws:

1. During rescans, the sort states were reset but then also set to NULL
   (despite the comment saying otherwise). ExecIncrementalSort then
   sees NULL and initializes a new sort state, leaking the memory used
   by the old one.

2. Initializing the sort state also automatically rebuilt the info about
   presorted keys, leaking the already initialized info. presorted_keys
   was also unnecessarily reset to NULL.

Patch by James Coleman, based on patches by Laurenz Albe and Tom Lane.
Backpatch to 13, where Incremental Sort was introduced.

Author: James Coleman, Laurenz Albe, Tom Lane
Reported-by: Laurenz Albe, Zu-Ming Jiang
Backpatch-through: 13
Discussion: https://postgr.es/m/b2bd02dff61af15e3526293e2771f874cf2a3be7.camel%40cybertec.at
Discussion: https://postgr.es/m/db03c582-086d-e7cd-d4a1-3bc722f81765%40inf.ethz.ch

Branch
------
REL_15_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/0c5fe4ff6b2b3daf08676d7939f1d7f3a6235212

Modified Files
--------------
src/backend/executor/nodeIncrementalSort.c | 7 -------
1 file changed, 7 deletions(-)