Merge branch 'bond_neigh_parms'

Veaceslav Falico says:

====================
Recent patches revealed an old bug, which was there for quite awhile. It's
related to vlan on top of bonding and ndo_neigh_setup(). When vlan device
is initiated, it calls its real_dev->ndo_neigh_setup(), and in case of
bonding - it will modify neigh_parms->neigh_setup to point to
bond_neigh_init, while neigh_parms are of vlan's dev.

This way, when neigh_parms->neigh_setup() of vlan's dev is called, the
bonding function will be called, which expects the dev to be struct
bonding, but will receive a vlan dev.

It was hidden before because of bond->first_slave usage. Now, with
Nikolay's conversion to list/RCU, first_slave is gone and we hit a null
pointer dereference when working with lists/slave.

First patch moves ndo_neigh_setup() in neigh_parms_alloc() to the bottom,
so that the ->dev will be available to the caller. It doesn't really change
anything, however is needed for the second patch.

Second patch makes bond_neigh_setup() (bond->ndo_neigh_setup()) check if
the neigh_parms are really from a bonding dev, and only modify the
neigh_setup in this case.
====================

Signed-off-by: David S. Miller <[email protected]>

drivers/net/bonding/bond_main.c

@@ -3630,11 +3630,17 @@ static int bond_neigh_init(struct neighbour *n)
  * The bonding ndo_neigh_setup is called at init time beofre any
  * slave exists. So we must declare proxy setup function which will
  * be used at run time to resolve the actual slave neigh param setup.
+ *
+ * It's also called by master devices (such as vlans) to setup their
+ * underlying devices. In that case - do nothing, we're already set up from
+ * our init.
  */
 static int bond_neigh_setup(struct net_device *dev,
 			    struct neigh_parms *parms)
 {
-	parms->neigh_setup   = bond_neigh_init;
+	/* modify only our neigh_parms */
+	if (parms->dev == dev)
+		parms->neigh_setup = bond_neigh_init;
 
 	return 0;
 }

net/core/neighbour.c

@@ -1441,16 +1441,18 @@ struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
 		atomic_set(&p->refcnt, 1);
 		p->reachable_time =
 				neigh_rand_reach_time(p->base_reachable_time);
+		dev_hold(dev);
+		p->dev = dev;
+		write_pnet(&p->net, hold_net(net));
+		p->sysctl_table = NULL;
 
 		if (ops->ndo_neigh_setup && ops->ndo_neigh_setup(dev, p)) {
+			release_net(net);
+			dev_put(dev);
 			kfree(p);
 			return NULL;
 		}
 
-		dev_hold(dev);
-		p->dev = dev;
-		write_pnet(&p->net, hold_net(net));
-		p->sysctl_table = NULL;
 		write_lock_bh(&tbl->lock);
 		p->next		= tbl->parms.next;
 		tbl->parms.next = p;