avcodec/mpeg12dec: Fix runtime error: left shift of negative value -1

Fixes: 764/clusterfuzz-testcase-6273034652483584

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2017-03-12 03:04:04 +01:00
parent 58f0bbc1ea
commit a720b854b0
1 changed files with 1 additions and 1 deletions

View File

@ -994,7 +994,7 @@ static int mpeg_decode_mb(MpegEncContext *s, int16_t block[12][64])
cbp = get_vlc2(&s->gb, ff_mb_pat_vlc.table, MB_PAT_VLC_BITS, 1);
if (mb_block_count > 6) {
cbp <<= mb_block_count - 6;
cbp *= 1 << mb_block_count - 6;
cbp |= get_bits(&s->gb, mb_block_count - 6);
s->bdsp.clear_blocks(s->block[6]);
}