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 <zealot0630@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
9cb6cb7ed1