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avcodec/mpeg4videodec: Fix integer overflow in mpeg4_decode_studio_block()

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Fixes: signed integer overflow: 24023040 * 112 cannot be represented in type 'int'
Fixes: 16570/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_fuzzer-5173275211071488

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Kieran Kunhya <kierank@obe.tv>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-08-23 00:23:52 +02:00
parent b6b9ac5698
commit 0e4a0e962c
1 changed files with 2 additions and 1 deletions
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3
libavcodec/mpeg4videodec.c
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@ -1826,6 +1826,7 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n
uint32_t flc;
const int min = -1 * (1 << (s->avctx->bits_per_raw_sample + 6));
const int max = ((1 << (s->avctx->bits_per_raw_sample + 6)) - 1);
int shift = 3 - s->dct_precision;
mismatch = 1;
@ -1921,7 +1922,7 @@ static int mpeg4_decode_studio_block(MpegEncContext *s, int32_t block[64], int n
else
block[j] = flc;
}
block[j] = ((8 * 2 * block[j] * quant_matrix[j] * s->qscale) >> s->dct_precision) / 32;
block[j] = ((block[j] * quant_matrix[j] * s->qscale) * (1 << shift)) / 16;
block[j] = av_clip(block[j], min, max);
mismatch ^= block[j];
}