[FFmpeg-cvslog] avcodec/mv30: Check remaining mask in decode_inter()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Mon Sep 14 00:03:36 2020 +0200| [142ae27b1d4d23b72396950ebaaeaca10ba600d9] | committer: Michael Niedermayer

avcodec/mv30: Check remaining mask in decode_inter()

Fixes: timeout (too long -> 4sec)
Fixes: 25129/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MV30_fuzzer-5642089713631232

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=142ae27b1d4d23b72396950ebaaeaca10ba600d9
---

 libavcodec/mv30.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libavcodec/mv30.c b/libavcodec/mv30.c
index c83ba7ffbd..0dcfef23e0 100644
--- a/libavcodec/mv30.c
+++ b/libavcodec/mv30.c
@@ -531,8 +531,13 @@ static int decode_inter(AVCodecContext *avctx, GetBitContext *gb,
         for (int x = 0; x < avctx->width; x += 16) {
             if (cnt >= 4)
                 cnt = 0;
-            if (cnt == 0)
+            if (cnt == 0) {
+                if (get_bits_left(&mask) < 8) {
+                    ret = AVERROR_INVALIDDATA;
+                    goto fail;
+                }
                 flags = get_bits(&mask, 8);
+            }
 
             dst[0] = frame->data[0] + linesize[0] * y + x;
             dst[1] = frame->data[0] + linesize[0] * y + x + 8;