commit 0553c891fabd287726b41076cfd03fe7e5ab596f
author Krishna Kumar <krkumar2@in.ibm.com> Thu Apr 14 06:07:04 2011 +0000
committer David S. Miller <davem@davemloft.net> Sun Apr 17 23:27:16 2011 -0700
tree 6b8b7074ff457e1533e8c397e09c03cd86ddc76e
parent 70dda99c41fc8a153e09bdba9adb7805ba2a4bb3

ip6_pol_route panic: Do not allow VLAN on loopback

Several tests in the ipv6 routing code check IFF_LOOPBACK, and
allowing stacking such as VLAN'ing on top of loopback results in a
netdevice which reports IFF_LOOPBACK but really isn't the loopback
device.

Instead of spamming the ipv6 routing code with even more special tests,
simply disallow VLAN over loopback.

The result of this patch is:

# modprobe 8021q
# vconfig add lo 43
ERROR: trying to add VLAN #43 to IF -:lo:-  error: Operation not supported

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/loopback.c

diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index ea0dc45..d70fb76 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -173,7 +173,8 @@
 		| NETIF_F_RXCSUM
 		| NETIF_F_HIGHDMA
 		| NETIF_F_LLTX
-		| NETIF_F_NETNS_LOCAL;
+		| NETIF_F_NETNS_LOCAL
+		| NETIF_F_VLAN_CHALLENGED;
 	dev->ethtool_ops	= &loopback_ethtool_ops;
 	dev->header_ops		= &eth_header_ops;
 	dev->netdev_ops		= &loopback_ops;