Commit 3bf74b1a authored Jun 17, 2013 by stephen hemminger Committed by David S. Miller Jun 17, 2013

vxlan: fix race between flush and incoming learning



It is possible for a packet to arrive during vxlan_stop(), and
have a dynamic entry created. Close this by checking if device
is up.

 CPU1                             CPU2
vxlan_stop
  vxlan_flush
     hash_lock acquired
                                  vxlan_encap_recv
                                     vxlan_snoop
                                        waiting for hash_lock
     hash_lock relased
  vxlan_flush done
                                        hash_lock acquired
                                        vxlan_fdb_create

This is a day-one bug in vxlan goes back to 3.7.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 8177a9d7

drivers/net/vxlan.c

+9 −7

Original line number	Diff line number	Diff line
		@@ -571,7 +571,6 @@ static void vxlan_snoop(struct net_device *dev,
		{
		struct vxlan_dev *vxlan = netdev_priv(dev);
		struct vxlan_fdb *f;
		int err;

		f = vxlan_find_mac(vxlan, src_mac);
		if (likely(f)) {
		@@ -588,7 +587,10 @@ static void vxlan_snoop(struct net_device *dev,
		} else {
		/* learned new entry */
		spin_lock(&vxlan->hash_lock);
		err = vxlan_fdb_create(vxlan, src_mac, src_ip,

		/* close off race between vxlan_flush and incoming packets */
		if (netif_running(dev))
		vxlan_fdb_create(vxlan, src_mac, src_ip,
		NUD_REACHABLE,
		NLM_F_EXCL\|NLM_F_CREATE,
		vxlan->dst_port,