From c8b835954ae4aef797112afda3b52f8dfe3c7b74 Mon Sep 17 00:00:00 2001
From: Laurent Aimar <fenrir@videolan.org>
Date: Wed, 28 Sep 2011 00:45:54 +0200
Subject: [PATCH] Check for out of bound reads in xan_huffman_decode() of the
 xan decoder.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
---
 libavcodec/xan.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libavcodec/xan.c b/libavcodec/xan.c
index fe11ac3f7a..21b5302000 100644
--- a/libavcodec/xan.c
+++ b/libavcodec/xan.c
@@ -114,7 +114,10 @@ static int xan_huffman_decode(unsigned char *dest, int dest_len,
     init_get_bits(&gb, ptr, ptr_len * 8);
 
     while ( val != 0x16 ) {
-        val = src[val - 0x17 + get_bits1(&gb) * byte];
+        unsigned idx = val - 0x17 + get_bits1(&gb) * byte;
+        if (idx >= 2 * byte)
+            return -1;
+        val = src[idx];
 
         if ( val < 0x16 ) {
             if (dest >= dest_end)