[FFmpeg-cvslog] avcodec/vc1: Check remaining bits in ff_vc1_parse_frame_header()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Mon Apr 19 15:50:43 2021 +0200| [38c47615880357314ba30727a85bf7b00989706a] | committer: Michael Niedermayer

avcodec/vc1: Check remaining bits in ff_vc1_parse_frame_header()

Fixes: Timeout
Fixes: 33156/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WMV3_fuzzer-6259655027326976

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=38c47615880357314ba30727a85bf7b00989706a
---

 libavcodec/vc1.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavcodec/vc1.c b/libavcodec/vc1.c
index b7140c089c..40e2b4d692 100644
--- a/libavcodec/vc1.c
+++ b/libavcodec/vc1.c
@@ -672,6 +672,8 @@ int ff_vc1_parse_frame_header(VC1Context *v, GetBitContext* gb)
     if (v->s.pict_type == AV_PICTURE_TYPE_P)
         v->rnd ^= 1;
 
+    if (get_bits_left(gb) < 5)
+        return AVERROR_INVALIDDATA;
     /* Quantizer stuff */
     pqindex = get_bits(gb, 5);
     if (!pqindex)
@@ -764,6 +766,9 @@ int ff_vc1_parse_frame_header(VC1Context *v, GetBitContext* gb)
         av_log(v->s.avctx, AV_LOG_DEBUG, "MB Skip plane encoding: "
                "Imode: %i, Invert: %i\n", status>>1, status&1);
 
+        if (get_bits_left(gb) < 4)
+            return AVERROR_INVALIDDATA;
+
         /* Hopefully this is correct for P-frames */
         v->s.mv_table_index = get_bits(gb, 2); //but using ff_vc1_ tables
         v->cbptab = get_bits(gb, 2);