diff options
| author | Andrea Arcangeli <aarcange@redhat.com> | 2011-10-31 17:08:22 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-10-31 17:30:47 -0700 |
| commit | ebed48460be5abd86d9a24fa7c66378e58109f30 (patch) | |
| tree | 721d935953c58ac014e3d00ea1092ab480ea3356 | |
| parent | 6661672053aee709d93f5dbd7887c789364c11d4 (diff) | |
| download | op-kernel-dev-ebed48460be5abd86d9a24fa7c66378e58109f30.zip op-kernel-dev-ebed48460be5abd86d9a24fa7c66378e58109f30.tar.gz | |
mremap: check for overflow using deltas
Using "- 1" relies on the old_end to be page aligned and PAGE_SIZE > 1,
those are reasonable requirements but the check remains obscure and it
looks more like an off by one error than an overflow check. This I feel
will improve readability.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/mremap.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/mremap.c b/mm/mremap.c index 506fa44..195e866 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -141,9 +141,10 @@ unsigned long move_page_tables(struct vm_area_struct *vma, for (; old_addr < old_end; old_addr += extent, new_addr += extent) { cond_resched(); next = (old_addr + PMD_SIZE) & PMD_MASK; - if (next - 1 > old_end) - next = old_end; + /* even if next overflowed, extent below will be ok */ extent = next - old_addr; + if (extent > old_end - old_addr) + extent = old_end - old_addr; old_pmd = get_old_pmd(vma->vm_mm, old_addr); if (!old_pmd) continue; |
