[PATCH 3.12 112/133] fib_frontend: fix possible NULL pointer dereference

Greg Kroah-Hartman
2014-02-04T21:58:11Z

From: Oliver Hartkopp <socketcan@hartkopp.net>

[ 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@hartkopp.net>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/fib_frontend.c | 2 ++
1 file changed, 2 insertions(+)

--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1049,6 +1049,8 @@ static int fib_netdev_event(struct notif
}

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

switch (event) {