From: Robert Haas <rhaas@postgresql.org>
Date: Thu, 15 Jan 2015 14:26:03 +0000 (-0500)
Subject: pg_standby: Avoid writing one byte beyond the end of the buffer.
X-Git-Tag: REL9_2_10~34
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d452bfd1b03a10498101d01a4337654c00bc26e6;p=thirdparty%2Fpostgresql.git

pg_standby: Avoid writing one byte beyond the end of the buffer.

Previously, read() might have returned a length equal to the buffer
length, and then the subsequent store to buf[len] would write a
zero-byte one byte past the end.  This doesn't seem likely to be
a security issue, but there's some chance it could result in
pg_standby misbehaving.

Spotted by Coverity; patch by Michael Paquier, reviewed by me.
---

diff --git a/contrib/pg_standby/pg_standby.c b/contrib/pg_standby/pg_standby.c
index bdb3362b4b6..ebd7f34b09c 100644
--- a/contrib/pg_standby/pg_standby.c
+++ b/contrib/pg_standby/pg_standby.c
@@ -435,7 +435,7 @@ CheckForExternalTrigger(void)
 		return;
 	}
 
-	if ((len = read(fd, buf, sizeof(buf))) < 0)
+	if ((len = read(fd, buf, sizeof(buf) - 1)) < 0)
 	{
 		fprintf(stderr, "WARNING: could not read \"%s\": %s\n",
 				triggerPath, strerror(errno));