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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2014-04-07 15:36:54 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-07 16:35:49 -0700
commita9af0c5dfdaf0b2e1a8bab7fbf6f29138947d534 (patch)
tree2de13aa7095ee0b4aa8a7d47d9d89817a06a52a6
parent87c1b497c299e48e681f041de4dd6ce4831aaf75 (diff)
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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>
-rw-r--r--mm/hugetlb.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7c02b9dadfb0..6cddfadaba03 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -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 */