From 24dc4afebd5a82f30aed6bd18d48ff42ef787410 Mon Sep 17 00:00:00 2001 From: Daniel Gustafsson Date: Thu, 29 Feb 2024 12:19:52 +0100 Subject: [PATCH] Fix integer underflow in shared memory debugging dsa_dump would print a large negative number instead of zero for segment bin 0. Fix by explicitly checking for underflow and add special case for bin 0. Backpatch to all supported versions. Author: Ian Ilyasov Reviewed-by: Robert Haas Discussion: https://postgr.es/m/GV1P251MB1004E0D09D117D3CECF9256ECD502@GV1P251MB1004.EURP251.PROD.OUTLOOK.COM Backpatch-through: v12 --- src/backend/utils/mmgr/dsa.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/src/backend/utils/mmgr/dsa.c b/src/backend/utils/mmgr/dsa.c index 35e166dd3d..564995db79 100644 --- a/src/backend/utils/mmgr/dsa.c +++ b/src/backend/utils/mmgr/dsa.c @@ -1093,9 +1093,13 @@ dsa_dump(dsa_area *area) { dsa_segment_index segment_index; - fprintf(stderr, - " segment bin %zu (at least %d contiguous pages free):\n", - i, 1 << (i - 1)); + if (i == 0) + fprintf(stderr, + " segment bin %zu (no contiguous free pages):\n", i); + else + fprintf(stderr, + " segment bin %zu (at least %d contiguous pages free):\n", + i, 1 << (i - 1)); segment_index = area->control->segment_bins[i]; while (segment_index != DSA_SEGMENT_INDEX_NONE) {