[FFmpeg-devel,1/5] avcodec/vc1: check REFDIST

Submitted by Michael Niedermayer on Aug. 31, 2019, 10:32 p.m.

Details

Message ID 20190831223240.27804-1-michael@niedermayer.cc
State New
Headers show

Commit Message

Michael Niedermayer Aug. 31, 2019, 10:32 p.m.
"9.1.1.43 P Reference Distance (REFDIST)"
"The value of REFDIST shall be less than, or equal to, 16."

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/vc1.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Michael Niedermayer Sept. 6, 2019, 8:29 p.m.
On Sun, Sep 01, 2019 at 12:32:40AM +0200, Michael Niedermayer wrote:
> Ask for a sample for these
> Fixes: out of array access
> Fixes: 16624/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5762455661182976
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavformat/vividas.c | 4 ++++
>  1 file changed, 4 insertions(+)

will apply

[...]

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diff --git a/libavcodec/vc1.c b/libavcodec/vc1.c
index e102b931d8..42bfca55b1 100644
--- a/libavcodec/vc1.c
+++ b/libavcodec/vc1.c
@@ -933,7 +933,9 @@  int ff_vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
         else if ((v->s.pict_type != AV_PICTURE_TYPE_B) && (v->s.pict_type != AV_PICTURE_TYPE_BI)) {
             v->refdist = get_bits(gb, 2);
             if (v->refdist == 3)
-                v->refdist += get_unary(gb, 0, 16);
+                v->refdist += get_unary(gb, 0, 14);
+            if (v->refdist > 16)
+                return AVERROR_INVALIDDATA;
         }
         if ((v->s.pict_type == AV_PICTURE_TYPE_B) || (v->s.pict_type == AV_PICTURE_TYPE_BI)) {
             if (read_bfraction(v, gb) < 0)