From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: linux-kernel@vger.kernel.org
Cc: akpm@linux-foundation.org, mgorman@suse.de, andi@firstfloor.org,
sasha.levin@oracle.com, kirill.shutemov@linux.intel.com,
aneesh.kumar@linux.vnet.ibm.com, linux-mm@kvack.org
Subject: [PATCH] mm/hugetlb.c: add NULL check of return value of huge_pte_offset
Date: Fri, 04 Apr 2014 14:43:33 -0400 [thread overview]
Message-ID: <533efd6b.46250e0a.4a07.5836SMTPIN_ADDED_BROKEN@mx.google.com> (raw)
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>
---
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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next reply other threads:[~2014-04-04 18:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-04 18:43 Naoya Horiguchi [this message]
[not found] <533efd68.435fe00a.6936.ffffa5e7SMTPIN_ADDED_BROKEN@mx.google.com>
2014-04-04 22:03 ` Andrew Morton
2014-04-05 0:04 ` Naoya Horiguchi
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