From 42110a6a6a3f15ea1ca1e81fbf3417322bdecff7 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 21 Aug 2007 02:40:33 +0000
Subject: [PATCH] Fix potential access-off-the-end-of-memory in varbit_out():
 it fetched the byte after the last full byte of the bit array, regardless of
 whether that byte was part of the valid data or not.  Found by buildfarm
 testing. Thanks to Stefan Kaltenbrunner for nailing down the cause.

---
 src/backend/utils/adt/varbit.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/backend/utils/adt/varbit.c b/src/backend/utils/adt/varbit.c
index 00527c45f18..0143e0aa9c6 100644
--- a/src/backend/utils/adt/varbit.c
+++ b/src/backend/utils/adt/varbit.c
@@ -9,7 +9,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/varbit.c,v 1.37 2003/09/25 06:58:05 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/varbit.c,v 1.37.2.1 2007/08/21 02:40:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -430,8 +430,9 @@ varbit_out(PG_FUNCTION_ARGS)
 	result = (char *) palloc(len + 1);
 	sp = VARBITS(s);
 	r = result;
-	for (i = 0; i < len - BITS_PER_BYTE; i += BITS_PER_BYTE, sp++)
+	for (i = 0; i <= len - BITS_PER_BYTE; i += BITS_PER_BYTE, sp++)
 	{
+		/* print full bytes */
 		x = *sp;
 		for (k = 0; k < BITS_PER_BYTE; k++)
 		{
@@ -439,11 +440,15 @@ varbit_out(PG_FUNCTION_ARGS)
 			x <<= 1;
 		}
 	}
-	x = *sp;
-	for (k = i; k < len; k++)
+	if (i < len)
 	{
-		*r++ = (x & BITHIGH) ? '1' : '0';
-		x <<= 1;
+		/* print the last partial byte */
+		x = *sp;
+		for (k = i; k < len; k++)
+		{
+			*r++ = (x & BITHIGH) ? '1' : '0';
+			x <<= 1;
+		}
 	}
 	*r = '\0';