[FFmpeg-cvslog] avcodec/vc1_block: Fix invalid left shift in vc1_decode_p_mb()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Wed Oct  2 19:53:44 2019 +0200| [2f588ccfb70cba54a7ea8e740110953da604c0e6] | committer: Michael Niedermayer

avcodec/vc1_block: Fix invalid left shift in vc1_decode_p_mb()

Fixes: left shift of negative value -6
Fixes: 17810/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1_fuzzer-5638541240958976

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2f588ccfb70cba54a7ea8e740110953da604c0e6
---

 libavcodec/vc1_block.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c
index fe7dbf8b1d..f1c9f41f30 100644
--- a/libavcodec/vc1_block.c
+++ b/libavcodec/vc1_block.c
@@ -1481,7 +1481,7 @@ static int vc1_decode_p_mb(VC1Context *v)
                     v->vc1dsp.vc1_inv_trans_8x8(v->block[v->cur_blk_idx][block_map[i]]);
                     if (v->rangeredfrm)
                         for (j = 0; j < 64; j++)
-                            v->block[v->cur_blk_idx][block_map[i]][j] <<= 1;
+                            v->block[v->cur_blk_idx][block_map[i]][j] *= 2;
                     block_cbp   |= 0xF << (i << 2);
                     block_intra |= 1 << i;
                 } else if (is_coded[i]) {