From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 13 Aug 2010 16:24:04 +0000 (-0700)
Subject: mm: fix missing page table unmap for stack guard page failure case
X-Git-Tag: v2.6.27.52~5
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b522544929b78f2a2a304b1b7c907f28c6f5dcdb;p=thirdparty%2Fkernel%2Fstable.git

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 4f3ab97b5fc05..7e308fc2f961b 100644
--- 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);