CVE-2014-XXXX: mm: fix locking DoS issue (rhbz 1093084 1093076)

2 files changed, 104 insertions, 0 deletions

diff --git a/kernel.spec b/kernel.spec
index 09236c62..0939e1fe 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -748,6 +748,9 @@ Patch25067: ACPICA-Tables-Fix-bad-pointer-issue-in-acpi_tb_parse_root_table.patc
 #rhbz 696821
 Patch25068: fanotify-fix-EOVERFLOW-on-64-bit.patch
 
+#CVE-2014-XXXX rhbz 1093076 1093084
+Patch25069: mm-try_to_unmap_cluster-should-lock_page-before-mloc.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -1450,6 +1453,9 @@ ApplyPatch ACPICA-Tables-Fix-bad-pointer-issue-in-acpi_tb_parse_root_table.patch
 #rhbz 696821
 ApplyPatch fanotify-fix-EOVERFLOW-on-64-bit.patch
 
+#CVE-2014-XXXX rhbz 1093076 1093084
+ApplyPatch mm-try_to_unmap_cluster-should-lock_page-before-mloc.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2261,6 +2267,9 @@ fi
 #                 ||----w |
 #                 ||     ||
 %changelog
+* Wed Apr 30 2014 Josh Boyer <jwboyer@fedoraproject.org>
+- CVE-2014-XXXX: mm: fix locking DoS issue (rhbz 1093084 1093076)
+
 * Mon Apr 28 2014 Justin M. Forbes <jforbes@fedoraproject.org> 3.14.2-200
 - Linux v3.14.2 (rhbz 1067071 1091722 906568)
 
diff --git a/mm-try_to_unmap_cluster-should-lock_page-before-mloc.patch b/mm-try_to_unmap_cluster-should-lock_page-before-mloc.patch
new file mode 100644
index 00000000..60804192
--- /dev/null
+++ b/mm-try_to_unmap_cluster-should-lock_page-before-mloc.patch
@@ -0,0 +1,95 @@
+Bugzilla: 1093084
+Upstream-status: 3.15 and stable CC'd
+
+From 57e68e9cd65b4b8eb4045a1e0d0746458502554c Mon Sep 17 00:00:00 2001
+From: Vlastimil Babka <vbabka@suse.cz>
+Date: Mon, 7 Apr 2014 15:37:50 -0700
+Subject: [PATCH] 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>
+---
+ mm/mlock.c |  2 ++
+ mm/rmap.c  | 14 ++++++++++++--
+ 2 files changed, 14 insertions(+), 2 deletions(-)
+
+diff --git a/mm/mlock.c b/mm/mlock.c
+index 4e1a68162285..b1eb53634005 100644
+--- a/mm/mlock.c
++++ b/mm/mlock.c
+@@ -79,6 +79,7 @@ void clear_page_mlock(struct page *page)
+  */
+ void mlock_vma_page(struct page *page)
+ {
++	/* Serialize with page migration */
+ 	BUG_ON(!PageLocked(page));
+ 
+ 	if (!TestSetPageMlocked(page)) {
+@@ -174,6 +175,7 @@ unsigned int munlock_vma_page(struct page *page)
+ 	unsigned int nr_pages;
+ 	struct zone *zone = page_zone(page);
+ 
++	/* For try_to_munlock() and to serialize with page migration */
+ 	BUG_ON(!PageLocked(page));
+ 
+ 	/*
+diff --git a/mm/rmap.c b/mm/rmap.c
+index 11cf322f8133..9c3e77396d1a 100644
+--- a/mm/rmap.c
++++ b/mm/rmap.c
+@@ -1332,9 +1332,19 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
+ 		BUG_ON(!page || PageAnon(page));
+ 
+ 		if (locked_vma) {
+-			mlock_vma_page(page);   /* no-op if already mlocked */
+-			if (page == check_page)
++			if (page == check_page) {
++				/* we know we have check_page locked */
++				mlock_vma_page(page);
+ 				ret = SWAP_MLOCK;
++			} else if (trylock_page(page)) {
++				/*
++				 * If we can lock the page, perform mlock.
++				 * Otherwise leave the page alone, it will be
++				 * eventually encountered again later.
++				 */
++				mlock_vma_page(page);
++				unlock_page(page);
++			}
+ 			continue;	/* don't unmap */
+ 		}
+ 
+-- 
+1.9.0
+