[FFmpeg-cvslog] avcodec/shorten: Check verbatim length

[Michael Niedermayer]

ffmpeg | branch: release/3.2 | Michael Niedermayer <michael at niedermayer.cc> | Sun Aug 12 22:43:33 2018 +0200| [f20a35a13e4b789ccdc0c4dba27025984792a623] | committer: Michael Niedermayer

avcodec/shorten: Check verbatim length

Fixes: Timeout
Fixes: 9252/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SHORTEN_fuzzer-5780720709533696

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 7007dabec08f2f9f81661e71ef482dde394e17a8)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f20a35a13e4b789ccdc0c4dba27025984792a623
---

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

diff --git a/libavcodec/shorten.c b/libavcodec/shorten.c
index 94deb0a316..77d66189e4 100644
--- a/libavcodec/shorten.c
+++ b/libavcodec/shorten.c
@@ -613,6 +613,11 @@ static int shorten_decode_frame(AVCodecContext *avctx, void *data,
             switch (cmd) {
             case FN_VERBATIM:
                 len = get_ur_golomb_shorten(&s->gb, VERBATIM_CKSIZE_SIZE);
+                if (len < 0 || len > get_bits_left(&s->gb)) {
+                    av_log(avctx, AV_LOG_ERROR, "verbatim length %d invalid\n",
+                           len);
+                    return AVERROR_INVALIDDATA;
+                }
                 while (len--)
                     get_ur_golomb_shorten(&s->gb, VERBATIM_BYTE_SIZE);
                 break;