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h264_cavlc: fix assertion failure due to reading too long vlc

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2013-03-28 03:16:01 +01:00
parent ea9a6709a9
commit 10ece44d09

View File

@ -549,9 +549,15 @@ static int decode_residual(H264Context *h, GetBitContext *gb, int16_t *block, in
if(prefix<15){
level_code = (prefix<<suffix_length) + get_bits(gb, suffix_length);
}else{
level_code = (15<<suffix_length) + get_bits(gb, prefix-3);
if(prefix>=16)
level_code = 15<<suffix_length;
if (prefix>=16) {
if(prefix > 25+3){
av_log(h->avctx, AV_LOG_ERROR, "Invalid level prefix\n");
return AVERROR_INVALIDDATA;
}
level_code += (1<<(prefix-3))-4096;
}
level_code += get_bits(gb, prefix-3);
}
mask= -(level_code&1);
level_code= (((2+level_code)>>1) ^ mask) - mask;