[2/3] mm: fix missing page table unmap for stack guard page failure case

From: Greg KH
Date: Fri Aug 13 2010 - 17:49:11 EST


2.6.27-stable review patch. If anyone has any objections, please let us know.

------------------

From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

commit 5528f9132cf65d4d892bcbc5684c61e7822b21e9 upstream.

.. which didn't show up in my tests because it's a no-op on x86-64 and
most other architectures. But we enter the function with the last-level
page table mapped, and should unmap it at exit.

Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
mm/memory.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2428,8 +2428,10 @@ static int do_anonymous_page(struct mm_s
spinlock_t *ptl;
pte_t entry;

- if (check_stack_guard_page(vma, address) < 0)
+ if (check_stack_guard_page(vma, address) < 0) {
+ pte_unmap(page_table);
return VM_FAULT_SIGBUS;
+ }

/* Allocate our own private page. */
pte_unmap(page_table);


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