[3.11.y.z extended stable] Patch "fib_frontend: fix possible NULL pointer dereference" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    fib_frontend: fix possible NULL pointer dereference

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 3b98dfe07f8af95b7e9f801209895833916442f4 Mon Sep 17 00:00:00 2001
From: Oliver Hartkopp <socketcan at hartkopp.net>
Date: Thu, 23 Jan 2014 10:19:34 +0100
Subject: fib_frontend: fix possible NULL pointer dereference

commit a0065f266a9b5d51575535a25c15ccbeed9a9966 upstream.

The two commits 0115e8e30d (net: remove delay at device dismantle) and
748e2d9396a (net: reinstate rtnl in call_netdevice_notifiers()) silently
removed a NULL pointer check for in_dev since Linux 3.7.

This patch re-introduces this check as it causes crashing the kernel when
setting small mtu values on non-ip capable netdevices.

Signed-off-by: Oliver Hartkopp <socketcan at hartkopp.net>
Acked-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/ipv4/fib_frontend.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index b3f627a..f7f8cff 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1049,6 +1049,8 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo
 	}

 	in_dev = __in_dev_get_rtnl(dev);
+	if (!in_dev)
+		return NOTIFY_DONE;

 	switch (event) {
 	case NETDEV_UP:
--
1.8.3.2