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celt_lpc: avoid overflows when computing lpcs in fixed point

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The LPCs are computed in 32-bit, so increase the allowed range from +/-8
to +/-64 to avoid overflows caught during fuzzing. Before downshifting
back down to the +/-8 range in the final 16-bit output, perform bandwidth
extension to avoid any additional overflow issues.
This commit is contained in:
Felicia Lim 2021-02-22 22:29:14 -08:00
parent 16286a25fd
commit 7b05f44f4b
No known key found for this signature in database
GPG key ID: FDBB8534FAD78B08
5 changed files with 108 additions and 7 deletions

45
celt/fixed_debug.h
View file

@ -410,6 +410,51 @@ static OPUS_INLINE short MULT16_16_16(int a, int b)
return res;
}
/* result fits in 32 bits */
static OPUS_INLINE int MULT32_32_32(opus_int64 a, opus_int64 b)
{
opus_int64 res;
if (!VERIFY_INT(a) || !VERIFY_INT(b))
{
fprintf (stderr, "MULT32_32_32: inputs are not int: %d %d\n", a, b);
#ifdef FIXED_DEBUG_ASSERT
celt_assert(0);
#endif
}
res = a*b;
if (!VERIFY_INT(res))
{
fprintf (stderr, "MULT32_32_32: output is not int: %d\n", res);
#ifdef FIXED_DEBUG_ASSERT
celt_assert(0);
#endif
}
celt_mips+=5;
return res;
}
static OPUS_INLINE int MULT32_32_Q16(opus_int64 a, opus_int64 b)
{
opus_int64 res;
if (!VERIFY_INT(a) || !VERIFY_INT(b))
{
fprintf (stderr, "MULT32_32_Q16: inputs are not int: %d %d\n", a, b);
#ifdef FIXED_DEBUG_ASSERT
celt_assert(0);
#endif
}
res = ((opus_int64)(a)*(opus_int64)(b)) >> 16;
if (!VERIFY_INT(res))
{
fprintf (stderr, "MULT32_32_Q16: output is not int: %d*%d=%d\n", a, b, (int)res);
#ifdef FIXED_DEBUG_ASSERT
celt_assert(0);
#endif
}
celt_mips+=5;
return res;
}
#define MULT16_16(a, b) MULT16_16_(a, b, __FILE__, __LINE__)
static OPUS_INLINE int MULT16_16_(int a, int b, char *file, int line)
{