From cf29f49d8ae00bb153c24b5c8a8f6cb150a91de8 Mon Sep 17 00:00:00 2001
From: Xi Wang <xi.wang@gmail.com>
Date: Tue, 22 Jan 2013 20:58:07 -0500
Subject: [PATCH] rtpenc: fix overflow checking in avc_mp4_find_startcode()
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The check `start + res < start' is broken since pointer overflow is
undefined behavior in C. Many compilers such as gcc/clang optimize
away this check.
Use `res > end - start' instead. Also change `res' to unsigned int
to avoid signed left-shift overflow.
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Martin Storsjö <martin@martin.st>
---
libavformat/rtpenc_h264.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/libavformat/rtpenc_h264.c b/libavformat/rtpenc_h264.c
index ac74074307..206d9bafa3 100644
--- a/libavformat/rtpenc_h264.c
+++ b/libavformat/rtpenc_h264.c
@@ -31,14 +31,14 @@
static const uint8_t *avc_mp4_find_startcode(const uint8_t *start, const uint8_t *end, int nal_length_size)
{
- int res = 0;
+ unsigned int res = 0;
if (end - start < nal_length_size)
return NULL;
while (nal_length_size--)
res = (res << 8) | *start++;
- if (start + res > end || res < 0 || start + res < start)
+ if (res > end - start)
return NULL;
return start + res;