3.8-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Zang MingJie <zealot0...@gmail.com>

[ Upstream commit 9cb6cb7ed11cd3b69c47bb414983603a6ff20b1d ]

The following script will produce a kernel oops:

    sudo ip netns add v
    sudo ip netns exec v ip ad add 127.0.0.1/8 dev lo
    sudo ip netns exec v ip link set lo up
    sudo ip netns exec v ip ro add 224.0.0.0/4 dev lo
    sudo ip netns exec v ip li add vxlan0 type vxlan id 42 group 239.1.1.1 dev 
lo
    sudo ip netns exec v ip link set vxlan0 up
    sudo ip netns del v

where inspect by gdb:

    Program received signal SIGSEGV, Segmentation fault.
    [Switching to Thread 107]
    0xffffffffa0289e33 in ?? ()
    (gdb) bt
    #0  vxlan_leave_group (dev=0xffff88001bafa000) at drivers/net/vxlan.c:533
    #1  vxlan_stop (dev=0xffff88001bafa000) at drivers/net/vxlan.c:1087
    #2  0xffffffff812cc498 in __dev_close_many 
(head=head@entry=0xffff88001f2e7dc8) at net/core/dev.c:1299
    #3  0xffffffff812cd920 in dev_close_many 
(head=head@entry=0xffff88001f2e7dc8) at net/core/dev.c:1335
    #4  0xffffffff812cef31 in rollback_registered_many 
(head=head@entry=0xffff88001f2e7dc8) at net/core/dev.c:4851
    #5  0xffffffff812cf040 in unregister_netdevice_many 
(head=head@entry=0xffff88001f2e7dc8) at net/core/dev.c:5752
    #6  0xffffffff812cf1ba in default_device_exit_batch 
(net_list=0xffff88001f2e7e18) at net/core/dev.c:6170
    #7  0xffffffff812cab27 in cleanup_net (work=<optimized out>) at 
net/core/net_namespace.c:302
    #8  0xffffffff810540ef in process_one_work (worker=0xffff88001ba9ed40, 
work=0xffffffff8167d020) at kernel/workqueue.c:2157
    #9  0xffffffff810549d0 in worker_thread 
(__worker=__worker@entry=0xffff88001ba9ed40) at kernel/workqueue.c:2276
    #10 0xffffffff8105870c in kthread (_create=0xffff88001f2e5d68) at 
kernel/kthread.c:168
    #11 <signal handler called>
    #12 0x0000000000000000 in ?? ()
    #13 0x0000000000000000 in ?? ()
    (gdb) fr 0
    #0  vxlan_leave_group (dev=0xffff88001bafa000) at drivers/net/vxlan.c:533
    533         struct sock *sk = vn->sock->sk;
    (gdb) l
    528 static int vxlan_leave_group(struct net_device *dev)
    529 {
    530         struct vxlan_dev *vxlan = netdev_priv(dev);
    531         struct vxlan_net *vn = net_generic(dev_net(dev), vxlan_net_id);
    532         int err = 0;
    533         struct sock *sk = vn->sock->sk;
    534         struct ip_mreqn mreq = {
    535                 .imr_multiaddr.s_addr   = vxlan->gaddr,
    536                 .imr_ifindex            = vxlan->link,
    537         };
    (gdb) p vn->sock
    $4 = (struct socket *) 0x0

The kernel calls `vxlan_exit_net` when deleting the netns before shutting down
vxlan interfaces. Later the removal of all vxlan interfaces, where `vn->sock`
is already gone causes the oops. so we should manually shutdown all interfaces
before deleting `vn->sock` as the patch does.

Signed-off-by: Zang MingJie <zealot0...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/net/vxlan.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1491,6 +1491,15 @@ static __net_init int vxlan_init_net(str
 static __net_exit void vxlan_exit_net(struct net *net)
 {
        struct vxlan_net *vn = net_generic(net, vxlan_net_id);
+       struct vxlan_dev *vxlan;
+       struct hlist_node *pos;
+       unsigned h;
+
+       rtnl_lock();
+       for (h = 0; h < VNI_HASH_SIZE; ++h)
+               hlist_for_each_entry(vxlan, pos, &vn->vni_list[h], hlist)
+                       dev_close(vxlan->dev);
+       rtnl_unlock();
 
        if (vn->sock) {
                sk_release_kernel(vn->sock->sk);


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