From 3ce761d5cafeb0d63f2cb0e9876ba1578c1333c5 Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Sun, 2 Jul 2023 18:54:09 +0200 Subject: [PATCH] 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 --- src/backend/executor/nodeIncrementalSort.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/src/backend/executor/nodeIncrementalSort.c b/src/backend/executor/nodeIncrementalSort.c index e3f1dfc8d43c1..4b90cff610ef2 100644 --- a/src/backend/executor/nodeIncrementalSort.c +++ b/src/backend/executor/nodeIncrementalSort.c @@ -1138,7 +1138,6 @@ ExecReScanIncrementalSort(IncrementalSortState *node) node->outerNodeDone = false; node->n_fullsort_remaining = 0; node->bound_Done = 0; - node->presorted_keys = NULL; node->execution_status = INCSORT_LOADFULLSORT; @@ -1151,15 +1150,9 @@ ExecReScanIncrementalSort(IncrementalSortState *node) * cause a leak. */ if (node->fullsort_state != NULL) - { tuplesort_reset(node->fullsort_state); - node->fullsort_state = NULL; - } if (node->prefixsort_state != NULL) - { tuplesort_reset(node->prefixsort_state); - node->prefixsort_state = NULL; - } /* * If chgParam of subnode is not null, theni the plan will be re-scanned