huge_pte_offset() could return NULL, so we need NULL check to avoid
potential NULL pointer dereferences.
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
mm/hugetlb.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7222247a590b..b8f2bde6ca53 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2662,7 +2662,8 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
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
@@ -2706,7 +2707,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
*/
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 */
--
1.9.0
--
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