[FFmpeg-cvslog] avcodec/mpeg4videodec: Check for bitstream overread in decode_vol_header()

[Michael Niedermayer]

ffmpeg | branch: release/2.1 | Michael Niedermayer <michaelni at gmx.at> | Thu Feb 20 05:48:54 2014 +0100| [ea7ccf3748452b614b6ae81fa814303a49733fc2] | committer: Michael Niedermayer

avcodec/mpeg4videodec: Check for bitstream overread in decode_vol_header()

Fixes out of array read
Fixes: 08e48e9daae7d8f8ab6dbe3919e797e5-asan_heap-oob_157461c_5295_cov_1266798650_firefing.mpg
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
(cherry picked from commit 3edc3b159503d512c919b3d5902f7026e961823a)

Conflicts:

	libavcodec/mpeg4videodec.c

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ea7ccf3748452b614b6ae81fa814303a49733fc2
---

 libavcodec/mpeg4videodec.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
index dd97bd7..7a4a441 100644
--- a/libavcodec/mpeg4videodec.c
+++ b/libavcodec/mpeg4videodec.c
@@ -1766,6 +1766,11 @@ static int decode_vol_header(MpegEncContext *s, GetBitContext *gb){
              s->quarter_sample= get_bits1(gb);
         else s->quarter_sample=0;
 
+        if (get_bits_left(gb) < 4) {
+            av_log(s->avctx, AV_LOG_ERROR, "VOL Header truncated\n");
+            return AVERROR_INVALIDDATA;
+        }
+
         if(!get_bits1(gb)){
             int pos= get_bits_count(gb);
             int estimation_method= get_bits(gb, 2);