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

[Anton Khirnov]

ffmpeg | branch: release/0.10 | Anton Khirnov <anton at khirnov.net> | Fri Nov 15 10:15:24 2013 +0100| [2cbc8dfeddcbe00ef5f112162912bb49c1dd6623] | committer: Reinhard Tartler

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=2cbc8dfeddcbe00ef5f112162912bb49c1dd6623
---

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

diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index ba8872c..f021e59 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -3919,7 +3919,7 @@ 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 - ff_h264_decode_rbsp_trailing(h, ptr + dst_length - 1));