From a02740e53fb7d1668e2d0ea1362743d23211d43d Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 2 Jan 2023 16:17:00 -0500 Subject: [PATCH] Avoid reference to nonexistent array element in ExecInitAgg(). When considering an empty grouping set, we fetched phasedata->eqfunctions[-1]. Because the eqfunctions array is palloc'd, that would always be an aset pointer in released versions, and thus the code accidentally failed to malfunction (since it would do nothing unless it found a null pointer). Nonetheless this seems like trouble waiting to happen, so add a check for length == 0. It's depressing that our valgrind testing did not catch this. Maybe we should reconsider the choice to not mark that word NOACCESS? Richard Guo Discussion: https://postgr.es/m/CAMbWs4-vZuuPOZsKOYnSAaPYGKhmacxhki+vpOKk0O7rymccXQ@mail.gmail.com --- src/backend/executor/nodeAgg.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c index 31609c60fc6..1fdfbd1eea7 100644 --- a/src/backend/executor/nodeAgg.c +++ b/src/backend/executor/nodeAgg.c @@ -3574,6 +3574,11 @@ ExecInitAgg(Agg *node, EState *estate, int eflags) { int length = phasedata->gset_lengths[i]; + /* nothing to do for empty grouping set */ + if (length == 0) + continue; + + /* if we already had one of this length, it'll do */ if (phasedata->eqfunctions[length - 1] != NULL) continue;