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comment __malloc_donate overflow logic

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This commit is contained in:
Rich Felker 2018-04-17 15:18:49 -04:00
parent ce7ae11acf
commit 14032c30e2
1 changed files with 3 additions and 0 deletions
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3
src/malloc/malloc.c
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@ -563,6 +563,9 @@ void __malloc_donate(char *start, char *end)
size_t align_start_up = (SIZE_ALIGN-1) & (-(uintptr_t)start - OVERHEAD);
size_t align_end_down = (SIZE_ALIGN-1) & (uintptr_t)end;
/* Getting past this condition ensures that the padding for alignment
* and header overhead will not overflow and will leave a nonzero
* multiple of SIZE_ALIGN bytes between start and end. */
if (end - start <= OVERHEAD + align_start_up + align_end_down)
return;
start += align_start_up + OVERHEAD;