ipvlan: Fix failure path in dev registration during link creation

When newlink creation fails at device-registration, the port->count
is decremented twice. Francesco Ruggeri (fruggeri@arista.com) found
this issue in Macvlan and the same exists in IPvlan driver too.

While fixing this issue I noticed another issue of missing unregister
in case of failure, so adding it to the fix which is similar to the
macvlan fix by Francesco in commit 308379607548 ("macvlan: fix failure
during registration v3")

Reported-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Mahesh Bandewar <maheshb@google.com>
CC: Eric Dumazet <edumazet@google.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 11 deletions

diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 57941d3f4227..1c4d395fbd49 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -113,6 +113,7 @@ static int ipvlan_init(struct net_device *dev)
 {
         struct ipvl_dev *ipvlan = netdev_priv(dev);
         const struct net_device *phy_dev = ipvlan->phy_dev;
+        struct ipvl_port *port = ipvlan->port;
 
         dev->state = (dev->state & ~IPVLAN_STATE_MASK) |
                      (phy_dev->state & IPVLAN_STATE_MASK);
@@ -128,6 +129,8 @@ static int ipvlan_init(struct net_device *dev)
         if (!ipvlan->pcpu_stats)
                 return -ENOMEM;
 
+        port->count += 1;
+
         return 0;
 }
 
@@ -481,27 +484,21 @@ static int ipvlan_link_new(struct net *src_net, struct net_device *dev,
 
         dev->priv_flags |= IFF_IPVLAN_SLAVE;
 
-        port->count += 1;
         err = register_netdevice(dev);
         if (err < 0)
-                goto ipvlan_destroy_port;
+                return err;
 
         err = netdev_upper_dev_link(phy_dev, dev);
-        if (err)
-                goto ipvlan_destroy_port;
+        if (err) {
+                unregister_netdevice(dev);
+                return err;
+        }
 
         list_add_tail_rcu(&ipvlan->pnode, &port->ipvlans);
         ipvlan_set_port_mode(port, mode);
 
         netif_stacked_transfer_operstate(phy_dev, dev);
         return 0;
-
-ipvlan_destroy_port:
-        port->count -= 1;
-        if (!port->count)
-                ipvlan_port_destroy(phy_dev);
-
-        return err;
 }
 
 static void ipvlan_link_delete(struct net_device *dev, struct list_head *head)