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

[Kamal Mostafa]

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-3.8.y-queue branch of the 3.8.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-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.18.

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

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 83764ba296c0d90503ec2ae0f9020911b91a1766 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

[ Upstream commit a0065f266a9b5d51575535a25c15ccbeed9a9966 ]

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: Kamal Mostafa <kamal 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 5cd75e2..93ea4a1 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1052,6 +1052,8 @@ 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