lp:~ubuntu-kernel/ubuntu/+source/linux/+git/quantal

Author: Vlastimil Babka
Author Date: 2014-05-08 09:28:02 UTC

mm: try_to_unmap_cluster() should lock_page() before mlocking

A BUG_ON(!PageLocked) was triggered in mlock_vma_page() by Sasha Levin
fuzzing with trinity. The call site try_to_unmap_cluster() does not lock
the pages other than its check_page parameter (which is already locked).

The BUG_ON in mlock_vma_page() is not documented and its purpose is
somewhat unclear, but apparently it serializes against page migration,
which could otherwise fail to transfer the PG_mlocked flag. This would
not be fatal, as the page would be eventually encountered again, but
NR_MLOCK accounting would become distorted nevertheless. This patch adds
a comment to the BUG_ON in mlock_vma_page() and munlock_vma_page() to that
effect.

The call site try_to_unmap_cluster() is fixed so that for page !=
check_page, trylock_page() is attempted (to avoid possible deadlocks as we
already have check_page locked) and mlock_vma_page() is performed only
upon success. If the page lock cannot be obtained, the page is left
without PG_mlocked, which is again not a problem in the whole unevictable
memory design.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(back ported from commit 57e68e9cd65b4b8eb4045a1e0d0746458502554c)
CVE-2014-3122
BugLink: http://bugs.launchpad.net/bugs/1316268
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Acked-by: Andy Whitcroft <andy.whitcroft@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

Author: Brad Figg
Author Date: 2014-05-15 20:52:30 UTC

UBUNTU: Ubuntu-3.5.0-51.76

Signed-off-by: Brad Figg <brad.figg@canonical.com>

Author: Paolo Pisati
Author Date: 2014-05-09 14:11:01 UTC

UBUNTU: Ubuntu-3.5.0-242.58

Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

Author: Andy Whitcroft
Author Date: 2012-10-09 19:31:43 UTC

UBUNTU: Lowlatency-3.5.0-17.17

Signed-off-by: Andy Whitcroft <apw@canonical.com>