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authorCarsten Otte <cotte@de.ibm.com>2009-02-04 15:12:16 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-02-05 12:56:48 -0800
commitab92661d5d9514647346047f30f67a7f35ffea67 (patch)
tree3ed67a71d7cce6dbd5b6bd559966f7fc137c8f00 /mm
parent777c6c5f1f6e757ae49ecca2ed72d6b1f523c007 (diff)
downloadlinux-ab92661d5d9514647346047f30f67a7f35ffea67.tar.gz
do_wp_page: fix regression with execute in place
Fix do_wp_page for VM_MIXEDMAP mappings. In the case where pfn_valid returns 0 for a pfn at the beginning of do_wp_page and the mapping is not shared writable, the code branches to label `gotten:' with old_page == NULL. In case the vma is locked (vma->vm_flags & VM_LOCKED), lock_page, clear_page_mlock, and unlock_page try to access the old_page. This patch checks whether old_page is valid before it is dereferenced. The regression was introduced by "mlock: mlocked pages are unevictable" (commit b291f000393f5a0b679012b39d79fbc85c018233). Signed-off-by: Carsten Otte <cotte@de.ibm.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: <stable@kernel.org> [2.6.28.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memory.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 22bfa7a47a0..baa999e87cd 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1999,7 +1999,7 @@ gotten:
* Don't let another task, with possibly unlocked vma,
* keep the mlocked page.
*/
- if (vma->vm_flags & VM_LOCKED) {
+ if ((vma->vm_flags & VM_LOCKED) && old_page) {
lock_page(old_page); /* for LRU manipulation */
clear_page_mlock(old_page);
unlock_page(old_page);