neighbor: Initialize protocol when new pneigh_entry are created

pneigh_lookup uses kmalloc versus kzalloc when new entries are allocated.
Given that the newly added protocol field needs to be initialized.

Fixes: df9b0e30d4 ("neighbor: Add protocol attribute")
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/neighbour.c

@@ -725,6 +725,7 @@ struct pneigh_entry * pneigh_lookup(struct neigh_table *tbl,
 	if (!n)
 		goto out;
 
+	n->protocol = 0;
 	write_pnet(&n->net, net);
 	memcpy(n->key, pkey, key_len);
 	n->dev = dev;