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Fix issue with malloc_extend_top

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- when calculating a correction to align next brk to page boundary,
  ensure that the correction is less than a page size
- if allocating the correction fails, ensure that the top size is
  set to brk + sbrk_size (minus any front alignment made)

Signed-off-by: Jeff Johnston <jjohnstn@redhat.com>
This commit is contained in:
Jeff Johnston 2018-05-24 23:53:15 -04:00
parent fcfea0ae2d
commit 4a3d0a5a5d
1 changed files with 6 additions and 1 deletions
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7
newlib/libc/stdlib/mallocr.c
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@ -2198,13 +2198,18 @@ static void malloc_extend_top(RARG nb) RDECL INTERNAL_SIZE_T nb;
/* Guarantee the next brk will be at a page boundary */ /* Guarantee the next brk will be at a page boundary */
correction += pagesz - ((POINTER_UINT)(brk + sbrk_size) & (pagesz - 1)); correction += pagesz - ((POINTER_UINT)(brk + sbrk_size) & (pagesz - 1));
/* To guarantee page boundary, correction should be less than pagesz */
correction &= (pagesz - 1);
/* Allocate correction */ /* Allocate correction */
new_brk = (char*)(MORECORE (correction)); new_brk = (char*)(MORECORE (correction));
if (new_brk == (char*)(MORECORE_FAILURE)) if (new_brk == (char*)(MORECORE_FAILURE))
{ {
correction = 0; correction = 0;
correction_failed = 1; correction_failed = 1;
new_brk = brk; new_brk = brk + sbrk_size;
if (front_misalign > 0)
new_brk -= (MALLOC_ALIGNMENT) - front_misalign;
} }
sbrked_mem += correction; sbrked_mem += correction;