[FFmpeg-cvslog] h264: check buffer size before accessing it

[Anton Khirnov]

ffmpeg | branch: release/1.1 | Anton Khirnov <anton at khirnov.net> | Fri Nov 15 10:15:24 2013 +0100| [af40847681b978441fdd25276685414f9e17820a] | committer: Sean McGovern

h264: check buffer size before accessing it

Fixes invalid reads.
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC:libav-stable at libav.org

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=af40847681b978441fdd25276685414f9e17820a
---

 libavcodec/h264.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index d6d3d42..20fa82c 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -3941,7 +3941,7 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
                 s->workaround_bugs |= FF_BUG_TRUNCATED;
 
             if (!(s->workaround_bugs & FF_BUG_TRUNCATED))
-                while (ptr[dst_length - 1] == 0 && dst_length > 0)
+                while (dst_length > 0 && ptr[dst_length - 1] == 0)
                     dst_length--;
             bit_length = !dst_length ? 0
                                      : (8 * dst_length -