Commit 6db92468 authored Dec 18, 2018 by Petr Machata Committed by David S. Miller Dec 18, 2018

vxlan: Fix error path in __vxlan_dev_create()



When a failure occurs in rtnl_configure_link(), the current code
calls unregister_netdevice() to roll back the earlier call to
register_netdevice(), and jumps to errout, which calls
vxlan_fdb_destroy().

However unregister_netdevice() calls transitively ndo_uninit, which is
vxlan_uninit(), and that already takes care of deleting the default FDB
entry by calling vxlan_fdb_delete_default(). Since the entry added
earlier in __vxlan_dev_create() is exactly the default entry, the
cleanup code in the errout block always leads to double free and thus a
panic.

Besides, since vxlan_fdb_delete_default() always destroys the FDB entry
with notification enabled, the deletion of the default entry is notified
even before the addition was notified.

Instead, move the unregister_netdevice() call after the manual destroy,
which solves both problems.

Fixes: 0241b836 ("vxlan: fix default fdb entry netlink notify ordering during netdev create")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 6ad0b5a4

drivers/net/vxlan.c

+10 −3

Original line number	Diff line number	Diff line
		@@ -3259,6 +3259,7 @@ static int __vxlan_dev_create(struct net net, struct net_device dev,
		struct vxlan_net *vn = net_generic(net, vxlan_net_id);
		struct vxlan_dev *vxlan = netdev_priv(dev);
		struct vxlan_fdb *f = NULL;
		bool unregister = false;
		int err;

		err = vxlan_dev_configure(net, dev, conf, false, extack);
		@@ -3284,12 +3285,11 @@ static int __vxlan_dev_create(struct net net, struct net_device dev,
		err = register_netdevice(dev);
		if (err)
		goto errout;
		unregister = true;

		err = rtnl_configure_link(dev, NULL);
		if (err) {
		unregister_netdevice(dev);
		if (err)
		goto errout;
		}

		/* notify default fdb entry */
		if (f)
		@@ -3297,9 +3297,16 @@ static int __vxlan_dev_create(struct net net, struct net_device dev,

		list_add(&vxlan->next, &vn->vxlan_list);
		return 0;

		errout:
		/* unregister_netdevice() destroys the default FDB entry with deletion
		* notification. But the addition notification was not sent yet, so
		* destroy the entry by hand here.
		*/
		if (f)
		vxlan_fdb_destroy(vxlan, f, false);
		if (unregister)
		unregister_netdevice(dev);
		return err;
		}

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