4.4-stable patches

added patches:
	mqueue-fix-a-use-after-free-in-sys_mq_notify.patch

diff --git a/queue-4.4/mqueue-fix-a-use-after-free-in-sys_mq_notify.patch b/queue-4.4/mqueue-fix-a-use-after-free-in-sys_mq_notify.patch
new file mode 100644 (file)
index 0000000..e5920c5
--- /dev/null
+++ b/queue-4.4/mqueue-fix-a-use-after-free-in-sys_mq_notify.patch
@@ -0,0 +1,49 @@
+From f991af3daabaecff34684fd51fac80319d1baad1 Mon Sep 17 00:00:00 2001
+From: Cong Wang <xiyou.wangcong@gmail.com>
+Date: Sun, 9 Jul 2017 13:19:55 -0700
+Subject: mqueue: fix a use-after-free in sys_mq_notify()
+
+From: Cong Wang <xiyou.wangcong@gmail.com>
+
+commit f991af3daabaecff34684fd51fac80319d1baad1 upstream.
+
+The retry logic for netlink_attachskb() inside sys_mq_notify()
+is nasty and vulnerable:
+
+1) The sock refcnt is already released when retry is needed
+2) The fd is controllable by user-space because we already
+   release the file refcnt
+
+so we when retry but the fd has been just closed by user-space
+during this small window, we end up calling netlink_detachskb()
+on the error path which releases the sock again, later when
+the user-space closes this socket a use-after-free could be
+triggered.
+
+Setting 'sock' to NULL here should be sufficient to fix it.
+
+Reported-by: GeneBlue <geneblue.mail@gmail.com>
+Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
+Cc: Andrew Morton <akpm@linux-foundation.org>
+Cc: Manfred Spraul <manfred@colorfullife.com>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ ipc/mqueue.c |    4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+--- a/ipc/mqueue.c
++++ b/ipc/mqueue.c
+@@ -1251,8 +1251,10 @@ retry:
+ 
+                       timeo = MAX_SCHEDULE_TIMEOUT;
+                       ret = netlink_attachskb(sock, nc, &timeo, NULL);
+-                      if (ret == 1)
++                      if (ret == 1) {
++                              sock = NULL;
+                               goto retry;
++                      }
+                       if (ret) {
+                               sock = NULL;
+                               nc = NULL;