Commit c6761cf5 authored Oct 30, 2019 by Taehee Yoo Committed by David S. Miller Oct 30, 2019

vxlan: fix unexpected failure of vxlan_changelink()



After commit 0ce1822c ("vxlan: add adjacent link to limit depth
level"), vxlan_changelink() could fail because of
netdev_adjacent_change_prepare().
netdev_adjacent_change_prepare() returns -EEXIST when old lower device
and new lower device are same.
(old lower device is "dst->remote_dev" and new lower device is "lowerdev")
So, before calling it, lowerdev should be NULL if these devices are same.

Test command1:
    ip link add dummy0 type dummy
    ip link add vxlan0 type vxlan dev dummy0 dstport 4789 vni 1
    ip link set vxlan0 type vxlan ttl 5
    RTNETLINK answers: File exists

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 0ce1822c ("vxlan: add adjacent link to limit depth level")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent dc99da4f

drivers/net/vxlan.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -3967,6 +3967,9 @@ static int vxlan_changelink(struct net_device dev, struct nlattr tb[],
		if (err)
		return err;

		if (dst->remote_dev == lowerdev)
		lowerdev = NULL;

		err = netdev_adjacent_change_prepare(dst->remote_dev, lowerdev, dev,
		extack);
		if (err)
		@@ -4008,10 +4011,10 @@ static int vxlan_changelink(struct net_device dev, struct nlattr tb[],
		mod_timer(&vxlan->age_timer, jiffies);

		netdev_adjacent_change_commit(dst->remote_dev, lowerdev, dev);
		if (lowerdev && lowerdev != dst->remote_dev)
		if (lowerdev && lowerdev != dst->remote_dev) {
		dst->remote_dev = lowerdev;

		netdev_update_lockdep_key(lowerdev);
		}
		vxlan_config_apply(dev, &conf, lowerdev, vxlan->net, true);
		return 0;
		}

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