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avcodec/scpr: check if total_freq is 0 in decode0

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Fixes SIGFPE, closes #6196.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
This commit is contained in:
Paul B Mahol 2017-02-27 13:50:08 +01:00
parent 33de0fee2c
commit 86ab6b6e08
1 changed files with 19 additions and 6 deletions
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25
libavcodec/scpr.c
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@ -63,7 +63,7 @@ typedef struct SCPRContext {
int cxshift;
int (*get_freq)(RangeCoder *rc, unsigned total_freq, unsigned *freq);
void (*decode)(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigned freq, unsigned total_freq);
int (*decode)(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigned freq, unsigned total_freq);
} SCPRContext;
static void init_rangecoder(RangeCoder *rc, GetByteContext *gb)
@ -130,7 +130,7 @@ static void reinit_tables(SCPRContext *s)
s->mv_model[1][512] = 512;
}
static void decode(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigned freq, unsigned total_freq)
static int decode(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigned freq, unsigned total_freq)
{
rc->code -= cumFreq * rc->range;
rc->range *= freq;
@ -140,6 +140,8 @@ static void decode(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigne
rc->code = (rc->code << 8) | byte;
rc->range <<= 8;
}
return 0;
}
static int get_freq(RangeCoder *rc, unsigned total_freq, unsigned *freq)
@ -157,9 +159,14 @@ static int get_freq(RangeCoder *rc, unsigned total_freq, unsigned *freq)
return 0;
}
static void decode0(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigned freq, unsigned total_freq)
static int decode0(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigned freq, unsigned total_freq)
{
int t = rc->range * (uint64_t)cumFreq / total_freq;
int t;
if (total_freq == 0)
return AVERROR_INVALIDDATA;
t = rc->range * (uint64_t)cumFreq / total_freq;
rc->code1 += t + 1;
rc->range = rc->range * (uint64_t)(freq + cumFreq) / total_freq - (t + 1);
@ -170,6 +177,8 @@ static void decode0(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsign
rc->code1 <<= 8;
rc->range <<= 8;
}
return 0;
}
static int get_freq0(RangeCoder *rc, unsigned total_freq, unsigned *freq)
@ -202,7 +211,8 @@ static int decode_value(SCPRContext *s, unsigned *cnt, unsigned maxc, unsigned s
break;
c++;
}
s->decode(gb, rc, cumfr, cnt_c, totfr);
if ((ret = s->decode(gb, rc, cumfr, cnt_c, totfr)) < 0)
return ret;
cnt[c] = cnt_c + step;
totfr += step;
@ -251,7 +261,10 @@ static int decode_unit(SCPRContext *s, PixelModel *pixel, unsigned step, unsigne
break;
c++;
}
s->decode(gb, rc, cumfr, cnt_c, totfr);
if ((ret = s->decode(gb, rc, cumfr, cnt_c, totfr)) < 0)
return ret;
pixel->freq[c] = cnt_c + step;
pixel->lookup[x] = cnt_x + step;
totfr += step;