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avutil/mem: use GCC builtins to check for overflow in av_size_mult()

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Signed-off-by: James Almer <jamrial@gmail.com>
This commit is contained in:
James Almer
2021-05-27 11:58:57 -03:00
parent 51f1194eda
commit baf5cc5b7a
1 changed files with 8 additions and 1 deletions
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9
libavutil/mem.h
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@@ -674,11 +674,18 @@ void *av_dynarray2_add(void **tab_ptr, int *nb_ptr, size_t elem_size,
*/ */
static inline int av_size_mult(size_t a, size_t b, size_t *r) static inline int av_size_mult(size_t a, size_t b, size_t *r)
{ {
size_t t = a * b; size_t t;
#if (!defined(__INTEL_COMPILER) && AV_GCC_VERSION_AT_LEAST(5,1)) || AV_HAS_BUILTIN(__builtin_mul_overflow)
if (__builtin_mul_overflow(a, b, &t))
return AVERROR(EINVAL);
#else
t = a * b;
/* Hack inspired from glibc: don't try the division if nelem and elsize /* Hack inspired from glibc: don't try the division if nelem and elsize
* are both less than sqrt(SIZE_MAX). */ * are both less than sqrt(SIZE_MAX). */
if ((a | b) >= ((size_t)1 << (sizeof(size_t) * 4)) && a && t / a != b) if ((a | b) >= ((size_t)1 << (sizeof(size_t) * 4)) && a && t / a != b)
return AVERROR(EINVAL); return AVERROR(EINVAL);
#endif
*r = t; *r = t;
return 0; return 0;
} }