[FFmpeg-cvslog] avcodec/cavsdec: Check alpha/beta offset

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Tue Feb 20 23:11:01 2018 +0100| [d81e0f925a94a3d4f2a1c85447dc1d938e1e4fe5] | committer: Michael Niedermayer

avcodec/cavsdec: Check alpha/beta offset

Fixes: Integer overflow
Fixes: 6183/clusterfuzz-testcase-minimized-6269224436629504

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 ae2eb04648839bfc6c61c32cb0f124e91bb7ff8e)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d81e0f925a94a3d4f2a1c85447dc1d938e1e4fe5
---

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

diff --git a/libavcodec/cavsdec.c b/libavcodec/cavsdec.c
index 3aec0dd5e5..289ed1b242 100644
--- a/libavcodec/cavsdec.c
+++ b/libavcodec/cavsdec.c
@@ -1068,6 +1068,11 @@ static int decode_pic(AVSContext *h)
     if (!h->loop_filter_disable && get_bits1(&h->gb)) {
         h->alpha_offset        = get_se_golomb(&h->gb);
         h->beta_offset         = get_se_golomb(&h->gb);
+        if (   h->alpha_offset < -64 || h->alpha_offset > 64
+            || h-> beta_offset < -64 || h-> beta_offset > 64) {
+            h->alpha_offset = h->beta_offset  = 0;
+            return AVERROR_INVALIDDATA;
+        }
     } else {
         h->alpha_offset = h->beta_offset  = 0;
     }