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authorDaniel Borkmann <dborkman@redhat.com>2014-01-17 12:55:06 +0100
committerDavid S. Miller <davem@davemloft.net>2014-01-17 18:49:18 -0800
commitfd27e0d44a893b45832df3cb8e021bd1d773a73f (patch)
treee75a6eed29d2a4adf0bc1e35afcc5be28ef4b65c /drivers/net/vxlan.c
parent7dd40c197cea4effe7469d1eb612fabd69eef989 (diff)
net: vxlan: do not use vxlan_net before checking event type
Jesse Brandeburg reported that commit acaf4e70997f caused a panic when adding a network namespace while vxlan module was present in the system: [<ffffffff814d0865>] vxlan_lowerdev_event+0xf5/0x100 [<ffffffff816e9e5d>] notifier_call_chain+0x4d/0x70 [<ffffffff810912be>] __raw_notifier_call_chain+0xe/0x10 [<ffffffff810912d6>] raw_notifier_call_chain+0x16/0x20 [<ffffffff815d9610>] call_netdevice_notifiers_info+0x40/0x70 [<ffffffff815d9656>] call_netdevice_notifiers+0x16/0x20 [<ffffffff815e1bce>] register_netdevice+0x1be/0x3a0 [<ffffffff815e1dce>] register_netdev+0x1e/0x30 [<ffffffff814cb94a>] loopback_net_init+0x4a/0xb0 [<ffffffffa016ed6e>] ? lockd_init_net+0x6e/0xb0 [lockd] [<ffffffff815d6bac>] ops_init+0x4c/0x150 [<ffffffff815d6d23>] setup_net+0x73/0x110 [<ffffffff815d725b>] copy_net_ns+0x7b/0x100 [<ffffffff81090e11>] create_new_namespaces+0x101/0x1b0 [<ffffffff81090f45>] copy_namespaces+0x85/0xb0 [<ffffffff810693d5>] copy_process.part.26+0x935/0x1500 [<ffffffff811d5186>] ? mntput+0x26/0x40 [<ffffffff8106a15c>] do_fork+0xbc/0x2e0 [<ffffffff811b7f2e>] ? ____fput+0xe/0x10 [<ffffffff81089c5c>] ? task_work_run+0xac/0xe0 [<ffffffff8106a406>] SyS_clone+0x16/0x20 [<ffffffff816ee689>] stub_clone+0x69/0x90 [<ffffffff816ee329>] ? system_call_fastpath+0x16/0x1b Apparently loopback device is being registered first and thus we receive an event notification when vxlan_net is not ready. Hence, when we call net_generic() and request vxlan_net_id, we seem to access garbage at that point in time. In setup_net() where we set up a newly allocated network namespace, we traverse the list of pernet ops ... list_for_each_entry(ops, &pernet_list, list) { error = ops_init(ops, net); if (error < 0) goto out_undo; } ... and loopback_net_init() is invoked first here, so in the middle of setup_net() we get this notification in vxlan. As currently we only care about devices that unregister, move access through net_generic() there. Fix is based on Cong Wang's proposal, but only changes what is needed here. It sucks a bit as we only work around the actual cure: right now it seems the only way to check if a netns actually finished traversing all init ops would be to check if it's part of net_namespace_list. But that I find quite expensive each time we go through a notifier callback. Anyway, did a couple of tests and it seems good for now. Fixes: acaf4e70997f ("net: vxlan: when lower dev unregisters remove vxlan dev as well") Reported-by: Jesse Brandeburg <jesse.brandeburg@intel.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Jesse Brandeburg <jesse.brandeburg@intel.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Tested-by: Jesse Brandeburg <jesse.brandeburg@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/vxlan.c')
-rw-r--r--drivers/net/vxlan.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index a2dee80e1fb8..d6ec71f9d2d6 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2681,10 +2681,12 @@ static int vxlan_lowerdev_event(struct notifier_block *unused,
unsigned long event, void *ptr)
{
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
- struct vxlan_net *vn = net_generic(dev_net(dev), vxlan_net_id);
+ struct vxlan_net *vn;
- if (event == NETDEV_UNREGISTER)
+ if (event == NETDEV_UNREGISTER) {
+ vn = net_generic(dev_net(dev), vxlan_net_id);
vxlan_handle_lowerdev_unregister(vn, dev);
+ }
return NOTIFY_DONE;
}