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enforce first null byte in CANARY

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+ added MI_CANARY_MASK to enforce the LSB is 0
This commit is contained in:
gfelber 2024-10-27 10:59:56 +01:00
parent 3cba10e510
commit eaafec4461
2 changed files with 2 additions and 1 deletions
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1
include/mimalloc/types.h
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@ -472,6 +472,7 @@ typedef struct mi_padding_s {
uint32_t canary; // encoded block value to check validity of the padding (in case of overflow) uint32_t canary; // encoded block value to check validity of the padding (in case of overflow)
uint32_t delta; // padding bytes before the block. (mi_usable_size(p) - delta == exact allocated bytes) uint32_t delta; // padding bytes before the block. (mi_usable_size(p) - delta == exact allocated bytes)
} mi_padding_t; } mi_padding_t;
#define MI_CANARY_MASK (0xffffff00)
#define MI_PADDING_SIZE (sizeof(mi_padding_t)) #define MI_PADDING_SIZE (sizeof(mi_padding_t))
#define MI_PADDING_WSIZE ((MI_PADDING_SIZE + MI_INTPTR_SIZE - 1) / MI_INTPTR_SIZE) #define MI_PADDING_WSIZE ((MI_PADDING_SIZE + MI_INTPTR_SIZE - 1) / MI_INTPTR_SIZE)
#else #else

2
src/alloc.c
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@ -99,7 +99,7 @@ extern inline void* _mi_page_malloc_zero(mi_heap_t* heap, mi_page_t* page, size_
mi_assert_internal(delta >= 0 && mi_page_usable_block_size(page) >= (size - MI_PADDING_SIZE + delta)); mi_assert_internal(delta >= 0 && mi_page_usable_block_size(page) >= (size - MI_PADDING_SIZE + delta));
#endif #endif
mi_track_mem_defined(padding,sizeof(mi_padding_t)); // note: re-enable since mi_page_usable_block_size may set noaccess mi_track_mem_defined(padding,sizeof(mi_padding_t)); // note: re-enable since mi_page_usable_block_size may set noaccess
padding->canary = (uint32_t)(mi_ptr_encode(page,block,page->keys)); padding->canary = (uint32_t)(mi_ptr_encode(page,block,page->keys)) & MI_CANARY_MASK;
padding->delta = (uint32_t)(delta); padding->delta = (uint32_t)(delta);
#if MI_PADDING_CHECK #if MI_PADDING_CHECK
if (!mi_page_is_huge(page)) { if (!mi_page_is_huge(page)) {