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Code Issues Releases Activity

avcodec/celp_math: avoid overflow in shift

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by making gain unsigned we have 1 bit more available
alternatively we can clip twice as in the g729 reference

Fixes: left shift of 23404 by 17 places cannot be represented in type 'int'
Fixes: 61728/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ACELP_KELVIN_fuzzer-6280412547383296

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 2023-09-07 02:13:13 +02:00
parent f1954ff8d1
commit 6580a7b2b2
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GPG Key ID: B18E8928B3948D64
2 changed files with 3 additions and 3 deletions
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2
libavcodec/celp_math.h
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@ -78,7 +78,7 @@ int64_t ff_dot_product(const int16_t *a, const int16_t *b, int length);
*
* @return value << offset, if offset>=0; value >> -offset - otherwise
*/
static inline int bidir_sal(int value, int offset)
static inline unsigned bidir_sal(unsigned value, int offset)
{
if(offset < 0) return value >> -offset;
else return value << offset;

4
libavcodec/g729postfilter.c
View File

@ -581,7 +581,7 @@ void ff_g729_postfilter(AudioDSPContext *adsp, int16_t* ht_prev_data, int* voici
int16_t ff_g729_adaptive_gain_control(int gain_before, int gain_after, int16_t *speech,
int subframe_size, int16_t gain_prev)
{
int gain; // (3.12)
unsigned gain; // (3.12)
int n;
int exp_before, exp_after;
@ -603,7 +603,7 @@ int16_t ff_g729_adaptive_gain_control(int gain_before, int gain_after, int16_t *
gain = ((gain_before - gain_after) << 14) / gain_after + 0x4000;
gain = bidir_sal(gain, exp_after - exp_before);
}
gain = av_clip_int16(gain);
gain = FFMIN(gain, 32767);
gain = (gain * G729_AGC_FAC1 + 0x4000) >> 15; // gain * (1-0.9875)
} else
gain = 0;