[FFmpeg-cvslog] h264_cavlc: check the size of the intra PCM data.

[Anton Khirnov]

ffmpeg | branch: release/1.1 | Anton Khirnov <anton at khirnov.net> | Fri Nov 15 09:42:26 2013 +0100| [b5275ca1a805436ca12540c34dd5ed1671877434] | committer: Sean McGovern

h264_cavlc: check the size of the intra PCM data.

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=b5275ca1a805436ca12540c34dd5ed1671877434
---

 libavcodec/h264_cavlc.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libavcodec/h264_cavlc.c b/libavcodec/h264_cavlc.c
index 0cc7214..c01e94b 100644
--- a/libavcodec/h264_cavlc.c
+++ b/libavcodec/h264_cavlc.c
@@ -770,6 +770,10 @@ decode_intra_mb:
 
         // We assume these blocks are very rare so we do not optimize it.
         align_get_bits(&s->gb);
+        if (get_bits_left(&s->gb) < mb_size) {
+            av_log(s->avctx, AV_LOG_ERROR, "Not enough data for an intra PCM block.\n");
+            return AVERROR_INVALIDDATA;
+        }
 
         // The pixels are stored in the same order as levels in h->mb array.
         for(x=0; x < mb_size; x++){