kernel-fs_pin: CVE-2015-4178

Fixes list corruption of m_list or s_list if unused

References:
http://seclists.org/oss-sec/2015/q2/640
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2015-4178

Upstream patch:
https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/
patch/?id=11bf6b1ea65f1580477827831d05711e5b87ac7b

Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
Signed-off-by: Huimin She <huimin.she@enea.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/recipes-kernel/linux/linux-hierofalcon-3.19/fs_pin-CVE-2015-4178.patch b/recipes-kernel/linux/linux-hierofalcon-3.19/fs_pin-CVE-2015-4178.patch
new file mode 100644
index 0000000..34b6d0b
--- /dev/null
+++ b/recipes-kernel/linux/linux-hierofalcon-3.19/fs_pin-CVE-2015-4178.patch
@@ -0,0 +1,47 @@
+From 11bf6b1ea65f1580477827831d05711e5b87ac7b Mon Sep 17 00:00:00 2001
+From: "Eric W. Biederman" <ebiederm@xmission.com>
+Date: Thu, 2 Apr 2015 16:35:48 -0500
+Subject: fs_pin: Allow for the possibility that m_list or s_list go unused.
+
+[ Upstream commit 820f9f147dcce2602eefd9b575bbbd9ea14f0953 ]
+
+This is needed to support lazily umounting locked mounts.  Because the
+entire unmounted subtree needs to stay together until there are no
+users with references to any part of the subtree.
+
+To support this guarantee that the fs_pin m_list and s_list nodes
+are initialized by initializing them in init_fs_pin allowing
+for the possibility that pin_insert_group does not touch them.
+
+Further use hlist_del_init in pin_remove so that there is
+a hlist_unhashed test before the list we attempt to update
+the previous list item.
+
+Fixes CVE-2015-4178.
+Upstream-Status: Backport
+
+Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
+Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
+Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
+---
+ fs/fs_pin.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/fs/fs_pin.c b/fs/fs_pin.c
+index 9368236..569bbd1 100644
+--- a/fs/fs_pin.c
++++ b/fs/fs_pin.c
+@@ -20,8 +20,8 @@ void pin_put(struct fs_pin *p)
+ void pin_remove(struct fs_pin *pin)
+ {
+        spin_lock(&pin_lock);
+-       hlist_del(&pin->m_list);
+-       hlist_del(&pin->s_list);
++       hlist_del_init(&pin->m_list);
++       hlist_del_init(&pin->s_list);
+        spin_unlock(&pin_lock);
+ }
+ 
+-- 
+cgit v0.11.2
+