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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>
This commit is contained in:
stephen hemminger 2013-06-17 12:09:57 -07:00 committed by David S. Miller
parent 8177a9d79c
commit 3bf74b1aec
1 changed files with 9 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/net/vxlan.c
View File

@ -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)) {
@ -588,12 +587,15 @@ 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,
NUD_REACHABLE,
NLM_F_EXCL|NLM_F_CREATE,
vxlan->dst_port,
vxlan->default_dst.remote_vni,
0, NTF_SELF);
/* 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,
vxlan->default_dst.remote_vni,
0, NTF_SELF);
spin_unlock(&vxlan->hash_lock);
}
}