From 6360a31a84efe69d155ed96306b9a931a40beab9 Mon Sep 17 00:00:00 2001
From: David Drysdale <drysdale@google.com>
Date: Fri, 20 Nov 2015 10:47:12 +0800
Subject: [PATCH] CVE-2015-7497 Avoid an heap buffer overflow in
 xmlDictComputeFastQKey

For https://bugzilla.gnome.org/show_bug.cgi?id=756528
It was possible to hit a negative offset in the name indexing
used to randomize the dictionary key generation
Reported and fix provided by David Drysdale @ Google

Upstream-Status: Backport

CVE-2015-7497

Signed-off-by: Armin Kuster <akuster@mvista.com>

---
 dict.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/dict.c b/dict.c
index 5f71d55..8c8f931 100644
--- a/dict.c
+++ b/dict.c
@@ -486,7 +486,10 @@ xmlDictComputeFastQKey(const xmlChar *prefix, int plen,
 	value += 30 * (*prefix);
 
     if (len > 10) {
-        value += name[len - (plen + 1 + 1)];
+        int offset = len - (plen + 1 + 1);
+	if (offset < 0)
+	    offset = len - (10 + 1);
+	value += name[offset];
         len = 10;
 	if (plen > 10)
 	    plen = 10;
-- 
2.3.5