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mm/hugetlb.c: add NULL check of return value of huge_pte_offset 

huge_pte_offset() could return NULL, so we need NULL check to avoid
potential NULL pointer dereferences.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Naoya Horiguchi 2014-04-07 15:36:54 -07:00 committed by Linus Torvalds
parent 87c1b497c2
commit a9af0c5dfd
1 changed files with 3 additions and 2 deletions
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5
mm/hugetlb.c
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@ -2690,7 +2690,8 @@ retry_avoidcopy:
BUG_ON(huge_pte_none(pte));
spin_lock(ptl);
ptep = huge_pte_offset(mm, address & huge_page_mask(h));
if (likely(pte_same(huge_ptep_get(ptep), pte)))
if (likely(ptep &&
pte_same(huge_ptep_get(ptep), pte)))
goto retry_avoidcopy;
/*
* race occurs while re-acquiring page table
@ -2734,7 +2735,7 @@ retry_avoidcopy:
*/
spin_lock(ptl);
ptep = huge_pte_offset(mm, address & huge_page_mask(h));
if (likely(pte_same(huge_ptep_get(ptep), pte))) {
if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
ClearPagePrivate(new_page);
/* Break COW */