From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 4 Aug 2015 16:58:54 +0000 (-0400)
Subject: Cap wal_buffers to avoid a server crash when it's set very large.
X-Git-Tag: REL9_1_19~70
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4e51ea8fd26f743d92cd35905eac334aafe2b1cc;p=thirdparty%2Fpostgresql.git

Cap wal_buffers to avoid a server crash when it's set very large.

It must be possible to multiply wal_buffers by XLOG_BLCKSZ without
overflowing int, or calculations in StartupXLOG will go badly wrong
and crash the server.  Avoid that by imposing a maximum value on
wal_buffers.  This will be just under 2GB, assuming the usual value
for XLOG_BLCKSZ.

Josh Berkus, per an analysis by Andrew Gierth.
---

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index a3e86223db7..00a635fff28 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -1964,7 +1964,7 @@ static struct config_int ConfigureNamesInt[] =
 			GUC_UNIT_XBLOCKS
 		},
 		&XLOGbuffers,
-		-1, -1, INT_MAX,
+		-1, -1, (INT_MAX / XLOG_BLCKSZ),
 		check_wal_buffers, NULL, NULL
 	},