[FFmpeg-cvslog] avcodec/mjpegdec: Check remaining bitstream in ljpeg_decode_yuv_scan()

[Michael Niedermayer]

ffmpeg | branch: release/3.1 | Michael Niedermayer <michael at niedermayer.cc> | Tue Jan 24 16:13:05 2017 +0100| [777f8b9fe1a0cf85beba1bbb0f0dd0ebb3073bae] | committer: Michael Niedermayer

avcodec/mjpegdec: Check remaining bitstream in ljpeg_decode_yuv_scan()

Fixes timeout
Fixes: 445/fuzz-3-ffmpeg_VIDEO_AV_CODEC_ID_MJPEG_fuzzer
Fixes: 456/fuzz-2-ffmpeg_VIDEO_AV_CODEC_ID_JPEGLS_fuzzer

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 755933cb5cd17decd1838d3d64e07d4157de5638)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=777f8b9fe1a0cf85beba1bbb0f0dd0ebb3073bae
---

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

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 059c1c6..bc3798d 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -1082,6 +1082,10 @@ static int ljpeg_decode_yuv_scan(MJpegDecodeContext *s, int predictor,
 
     for (mb_y = 0; mb_y < s->mb_height; mb_y++) {
         for (mb_x = 0; mb_x < s->mb_width; mb_x++) {
+            if (get_bits_left(&s->gb) < 1) {
+                av_log(s->avctx, AV_LOG_ERROR, "bitstream end in yuv_scan\n");
+                return AVERROR_INVALIDDATA;
+            }
             if (s->restart_interval && !s->restart_count){
                 s->restart_count = s->restart_interval;
                 resync_mb_x = mb_x;