From: Thomas Munro <tmunro@postgresql.org>
Date: Sun, 10 Jun 2018 08:30:25 +0000 (+1200)
Subject: Limit Parallel Hash's bucket array to MaxAllocSize.
X-Git-Tag: REL_11_BETA2~86
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=86a2218eb00eb6f97898945967c5f9c95c72b4c6;p=postgresql

Limit Parallel Hash's bucket array to MaxAllocSize.

Make sure that we don't exceed MaxAllocSize when increasing the number of
buckets.  Perhaps later we'll remove that limit and use DSA_ALLOC_HUGE, but
for now just prevent further increases like the non-parallel code.  This
change avoids the error from bug report #15225.

Author: Thomas Munro
Reviewed-By: Tom Lane
Reported-by: Frits Jalvingh
Discussion: https://postgr.es/m/152802081668.26724.16985037679312485972%40wrigleys.postgresql.org
---

diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 4f069d17fd..6ffaa751f2 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -2818,9 +2818,12 @@ ExecParallelHashTupleAlloc(HashJoinTable hashtable, size_t size,
 		{
 			hashtable->batches[0].shared->ntuples += hashtable->batches[0].ntuples;
 			hashtable->batches[0].ntuples = 0;
+			/* Guard against integer overflow and alloc size overflow */
 			if (hashtable->batches[0].shared->ntuples + 1 >
 				hashtable->nbuckets * NTUP_PER_BUCKET &&
-				hashtable->nbuckets < (INT_MAX / 2))
+				hashtable->nbuckets < (INT_MAX / 2) &&
+				hashtable->nbuckets * 2 <=
+				MaxAllocSize / sizeof(dsa_pointer_atomic))
 			{
 				pstate->growth = PHJ_GROWTH_NEED_MORE_BUCKETS;
 				LWLockRelease(&pstate->lock);