avcodec/ilbcdec: Fix undefined integer overflow lsf2poly()

The addition is moved up into the context where the variable is unsigned avoiding
the undefined behavior

Fixes: runtime error: signed integer overflow: 2147481972 + 4096 cannot be represented in type 'int'
Fixes: 12444/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ILBC_fuzzer-5755706244857856

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 2019-01-15 00:09:30 +01:00
parent c95d0fb239
commit 4523cc5e75

View File

@ -408,11 +408,11 @@ static void lsf2poly(int16_t *a, int16_t *lsf)
a[0] = 4096;
for (i = 5; i > 0; i--) {
tmp = f[0][6 - i] + (unsigned)f[1][6 - i];
a[6 - i] = (tmp + 4096) >> 13;
tmp = f[0][6 - i] + (unsigned)f[1][6 - i] + 4096;
a[6 - i] = tmp >> 13;
tmp = f[0][6 - i] - (unsigned)f[1][6 - i];
a[5 + i] = (tmp + 4096) >> 13;
tmp = f[0][6 - i] - (unsigned)f[1][6 - i] + 4096;
a[5 + i] = tmp >> 13;
}
}