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avcodec/g729dec: Use 64bit and clip in scalar product

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The G729 reference decoder clips after each individual operation and keeps track if overflow
occurred (in the fixed point implementation), this here is
simpler and faster but not 1:1 the same what the reference does.

Non fuzzed samples which trigger any such overflow are welcome, so
the need and impact of different clipping solutions can be evaluated.

Fixes: signed integer overflow: 1271483721 + 1073676289 cannot be represented in type 'int'
Fixes: 18617/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ACELP_KELVIN_fuzzer-5137705679978496

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 bf9c4a12750e593d753011166b066efce208d9e0)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-11-05 23:28:35 +01:00
parent 34e6544424
commit 2f5dbf9b15
1 changed files with 4 additions and 1 deletions
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5
libavcodec/g729dec.c
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@ -328,11 +328,14 @@ static int16_t g729d_voice_decision(int onset, int prev_voice_decision, const in
static int32_t scalarproduct_int16_c(const int16_t * v1, const int16_t * v2, int order)
{
int res = 0;
int64_t res = 0;
while (order--)
res += *v1++ * *v2++;
if (res > INT32_MAX) return INT32_MAX;
else if (res < INT32_MIN) return INT32_MIN;
return res;
}