Messages in this thread Patch in this message | | | Date | Thu, 07 Jun 2012 13:03:42 +0900 | From | Greg KH <> | Subject | [ 06/82] mm: fix NULL ptr deref when walking hugepages |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Sasha Levin <levinsasha928@gmail.com>
commit 08fa29d916c6e271ad13978cd993e7238c68db97 upstream.
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> 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>
--- fs/proc/task_mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -784,7 +784,7 @@ static int pagemap_pte_range(pmd_t *pmd, /* 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;
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