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avcodec/dstdec: Check that AC probabilities are within range

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ISO/IEC 14496-3:2005(E): "Each entry of P_one[ ][ ] is in the range of 1 to
128, corresponding to a probability of 1/256 to 128/256 of the next error bit (bit E, See Figure 10.5)..."

Fixes: Timeout (42sec ->1sec)
Fixes: 18181/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DST_fuzzer-5736646250594304

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 0c3e1b395b)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-10-15 23:42:50 +02:00
parent a06c0fadc8
commit f9738b2af3
1 changed files with 4 additions and 0 deletions
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libavcodec/dstdec.c
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@ -161,6 +161,10 @@ static int read_table(GetBitContext *gb, Table *t, const int8_t code_pred_coeff[
c -= (x + 4) / 8;
else
c += (-x + 3) / 8;
if (!is_signed) {
if (c < offset || c >= offset + (1<<coeff_bits))
return AVERROR_INVALIDDATA;
}
t->coeff[i][j] = c;
}
}