[FFmpeg-cvslog] avcodec/mjpegdec: Check for bits left in mjpeg_decode_scan_progressive_ac()

[Michael Niedermayer]

ffmpeg | branch: release/4.4 | Michael Niedermayer <michael at niedermayer.cc> | Sun Aug 22 20:47:00 2021 +0200| [af8de920b7bdf6f5dfb34d3fd2e31e24fe50fb60] | committer: Michael Niedermayer

avcodec/mjpegdec: Check for bits left in mjpeg_decode_scan_progressive_ac()

Fixes: Timeout
Fixes: 36262/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEGLS_fuzzer-4969052454912000

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 909faca929cf30dcd439fa33479177e76fb5121d)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=af8de920b7bdf6f5dfb34d3fd2e31e24fe50fb60
---

 libavcodec/mjpegdec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 2df6caa440..afb117cfc6 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -1573,6 +1573,9 @@ static int mjpeg_decode_scan_progressive_ac(MJpegDecodeContext *s, int ss,
                 else
                     ret = decode_block_progressive(s, *block, last_nnz, s->ac_index[0],
                                                    quant_matrix, ss, se, Al, &EOBRUN);
+
+                if (ret >= 0 && get_bits_left(&s->gb) < 0)
+                    ret = AVERROR_INVALIDDATA;
                 if (ret < 0) {
                     av_log(s->avctx, AV_LOG_ERROR,
                            "error y=%d x=%d\n", mb_y, mb_x);