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_0_23~66
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b09446ed7eecc7cee6f7cc1dcc954c75c6c7570b;p=postgresql

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 203f202663..597ac8885e 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -1722,7 +1722,7 @@ static struct config_int ConfigureNamesInt[] =
 			GUC_UNIT_XBLOCKS
 		},
 		&XLOGbuffers,
-		8, 4, INT_MAX, NULL, NULL
+		8, 4, (INT_MAX / XLOG_BLCKSZ), NULL, NULL
 	},
 
 	{