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avcodec/vc1_block: Fix integer overflow in AC rescaling in vc1_decode_i_block_adv() 

Fixes: signed integer overflow: 50176 * 262144 cannot be represented in type 'int'
Fixes: 18629/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1IMAGE_fuzzer-5182370286403584

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-11-08 18:31:02 +01:00
parent 47d963335e
commit 0e010e489b
1 changed files with 1 additions and 1 deletions
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2
libavcodec/vc1_block.c
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@ -889,7 +889,7 @@ static int vc1_decode_i_block_adv(VC1Context *v, int16_t block[64], int n,
q2 = FFABS(q2) * 2 + ((q2 < 0) ? 0 : v->halfpq) - 1;
if (q2 && q1 != q2) {
for (k = 1; k < 8; k++)
ac_val2[k] = (ac_val2[k] * q2 * ff_vc1_dqscale[q1 - 1] + 0x20000) >> 18;
ac_val2[k] = (int)(ac_val2[k] * q2 * (unsigned)ff_vc1_dqscale[q1 - 1] + 0x20000) >> 18;
}
for (k = 1; k < 8; k++) {
block[k << sh] = ac_val2[k] * scale;