Commit 5da9828c authored Mar 16, 2019 by Zhiqiang Liu Committed by Greg Kroah-Hartman Apr 03, 2019

vxlan: Don't call gro_cells_destroy() before device is unregistered



[ Upstream commit cc4807bb609230d8959fd732b0bf3bd4c2de8eac ]

Commit ad6c9986bcb62 ("vxlan: Fix GRO cells race condition between
receive and link delete") fixed a race condition for the typical case a vxlan
device is dismantled from the current netns. But if a netns is dismantled,
vxlan_destroy_tunnels() is called to schedule a unregister_netdevice_queue()
of all the vxlan tunnels that are related to this netns.

In vxlan_destroy_tunnels(), gro_cells_destroy() is called and finished before
unregister_netdevice_queue(). This means that the gro_cells_destroy() call is
done too soon, for the same reasons explained in above commit.

So we need to fully respect the RCU rules, and thus must remove the
gro_cells_destroy() call or risk use after-free.

Fixes: 58ce31cc ("vxlan: GRO support at tunnel layer")
Signed-off-by: Suanming.Mou <mousuanming@huawei.com>
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 5018d910

drivers/net/vxlan.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -3375,11 +3375,9 @@ static void __net_exit vxlan_exit_net(struct net *net)
		/* If vxlan->dev is in the same netns, it has already been added
		* to the list by the previous loop.
		*/
		if (!net_eq(dev_net(vxlan->dev), net)) {
		gro_cells_destroy(&vxlan->gro_cells);
		if (!net_eq(dev_net(vxlan->dev), net))
		unregister_netdevice_queue(vxlan->dev, &list);
		}
		}

		unregister_netdevice_many(&list);
		rtnl_unlock();