From: Jianguo Wu <wujianguo@huawei.com>
Date: Thu, 19 Dec 2013 01:08:59 +0000 (-0800)
Subject: mm/hugetlb: check for pte NULL pointer in __page_check_address()
X-Git-Tag: v3.4.76~11
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2efb73fb4f0f5081ba6450e789b52f70247c80d9;p=platform%2Fkernel%2Flinux-stable.git

mm/hugetlb: check for pte NULL pointer in __page_check_address()

commit 98398c32f6687ee1e1f3ae084effb4b75adb0747 upstream.

In __page_check_address(), if address's pud is not present,
huge_pte_offset() will return NULL, we should check the return value.

Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: qiuxishi <qiuxishi@huawei.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/mm/rmap.c b/mm/rmap.c
index bfca52c..f02c862 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -623,7 +623,11 @@ pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
 	spinlock_t *ptl;
 
 	if (unlikely(PageHuge(page))) {
+		/* when pud is not present, pte will be NULL */
 		pte = huge_pte_offset(mm, address);
+		if (!pte)
+			return NULL;
+
 		ptl = &mm->page_table_lock;
 		goto check;
 	}