mm: fix missing page table unmap for stack guard page failure case

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@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/mm/memory.c b/mm/memory.c
index 4f3ab97..7e308fc 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2428,8 +2428,10 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
        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);