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fix overflow on arm32

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Previously we were dividing MI_SEGMENT_MAP_PART_SIZE (in bytes) by (MI_SEGMENT_MAP_PART_BITS * MI_SEGMENT_MAP_PART_BIT_SPAN) (in bits). Not to say that it looks incorrect, it also results in UB when MI_SEGMENT_MAP_PART_SIZE is 2^32 (32bit system).
This commit is contained in:
Eduard Voronkin 2025-02-21 17:08:57 -08:00
parent 01afcaacf6
commit 86ed2e9db2
1 changed files with 5 additions and 10 deletions
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15
src/segment-map.c
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@ -25,16 +25,11 @@ terms of the MIT license. A copy of the license can be found in the file
#define MI_SEGMENT_MAP_MAX_ADDRESS (UINT32_MAX)
#endif
#define MI_SEGMENT_MAP_PART_SIZE (MI_INTPTR_SIZE*MI_KiB - 128) // 128 > sizeof(mi_memid_t) !
#define MI_SEGMENT_MAP_PART_BITS (8*MI_SEGMENT_MAP_PART_SIZE)
#define MI_SEGMENT_MAP_PART_ENTRIES (MI_SEGMENT_MAP_PART_SIZE / MI_INTPTR_SIZE)
#define MI_SEGMENT_MAP_PART_BIT_SPAN (MI_SEGMENT_ALIGN)
#define MI_SEGMENT_MAP_PART_SIZE \
(MI_INTPTR_SIZE * MI_KiB - 128) // 128 > sizeof(mi_memid_t) !
#define MI_SEGMENT_MAP_PART_ENTRIES (MI_SEGMENT_MAP_PART_SIZE / MI_INTPTR_SIZE)
#if (MI_SEGMENT_PART_BITS < (MI_SEGMENT_MAP_MAX_ADDRESS / MI_SEGMENT_MAP_PART_BIT_SPAN)) // prevent overflow on 32-bit (issue #1017)
#define MI_SEGMENT_MAP_PART_SPAN (MI_SEGMENT_MAP_PART_BITS * MI_SEGMENT_MAP_PART_BIT_SPAN)
#else
#define MI_SEGMENT_MAP_PART_SPAN MI_SEGMENT_MAP_MAX_ADDRESS
#endif
#define MI_SEGMENT_MAP_PART_SPAN (MI_SEGMENT_MAP_PART_SIZE * MI_SEGMENT_ALIGN)
#define MI_SEGMENT_MAP_MAX_PARTS ((MI_SEGMENT_MAP_MAX_ADDRESS / MI_SEGMENT_MAP_PART_SPAN) + 1)
@ -73,7 +68,7 @@ static mi_segmap_part_t* mi_segment_map_index_of(const mi_segment_t* segment, bo
}
mi_assert(part != NULL);
const uintptr_t offset = ((uintptr_t)segment) % MI_SEGMENT_MAP_PART_SPAN;
const uintptr_t bitofs = offset / MI_SEGMENT_MAP_PART_BIT_SPAN;
const uintptr_t bitofs = offset / MI_SEGMENT_ALIGN;
*idx = bitofs / MI_INTPTR_BITS;
*bitidx = bitofs % MI_INTPTR_BITS;
return part;