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| author | Sasha Levin <levinsasha928@gmail.com> | 2012-05-29 15:06:15 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-05-29 16:22:18 -0700 |
| commit | 08fa29d916c6e271ad13978cd993e7238c68db97 (patch) | |
| tree | a7f7aa9a3a468cba985e5a26551b504f48e2922e /fs/proc | |
| parent | 4c9c6a1bc869daeb1575442cbf94ba5878c08a67 (diff) | |
| download | linux-08fa29d916c6e271ad13978cd993e7238c68db97.tar.bz2 | |
mm: fix NULL ptr deref when walking hugepages
A missing validation of the value returned by find_vma() could cause a
NULL ptr dereference when walking the pagetable.
This is triggerable from usermode by a simple user by trying to read a
page info out of /proc/pid/pagemap which doesn't exist.
Introduced by commit 025c5b2451e4 ("thp: optimize away unnecessary page
table locking").
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: <stable@vger.kernel.org> [3.4.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/task_mmu.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 1030a716d155..7faaf2acc570 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -784,7 +784,7 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, /* find the first VMA at or above 'addr' */ vma = find_vma(walk->mm, addr); - if (pmd_trans_huge_lock(pmd, vma) == 1) { + if (vma && pmd_trans_huge_lock(pmd, vma) == 1) { for (; addr != end; addr += PAGE_SIZE) { unsigned long offset; |