[FFmpeg-cvslog] avcodec/mjpegdec: Check for end of bitstream in ljpeg_decode_rgb_scan()

[Michael Niedermayer]

ffmpeg | branch: release/4.0 | Michael Niedermayer <michael at niedermayer.cc> | Thu Jun 21 22:48:54 2018 +0200| [2c404cc11a02d8b4368080fe3268f652fb2d998b] | committer: Michael Niedermayer

avcodec/mjpegdec: Check for end of bitstream in ljpeg_decode_rgb_scan()

Fixes: Timeout
Fixes: 8648/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MJPEG_fuzzer-5108395525799936

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 540e8c2d641bf90fc28e47e170f8c0b1962197e9)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2c404cc11a02d8b4368080fe3268f652fb2d998b
---

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

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index d1dca84d36..00cfdd7151 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -1055,6 +1055,11 @@ static int ljpeg_decode_rgb_scan(MJpegDecodeContext *s, int nb_components, int p
         for (mb_x = 0; mb_x < s->mb_width; mb_x++) {
             int modified_predictor = predictor;
 
+            if (get_bits_left(&s->gb) < 1) {
+                av_log(s->avctx, AV_LOG_ERROR, "bitstream end in rgb_scan\n");
+                return AVERROR_INVALIDDATA;
+            }
+
             if (s->restart_interval && !s->restart_count){
                 s->restart_count = s->restart_interval;
                 resync_mb_x = mb_x;