[IPV6] MCAST: Fix joining all-node multicast group on device initialization.

Join all-node multicast group after assignment of dev->ip6_ptr
because it must be assigned when ipv6_dev_mc_inc() is called.
This fixes Bug#7817, reported by <gernoth@informatik.uni-erlangen.de>.

Closes: 7817
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 171e5b5..2a7e461 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -341,6 +341,7 @@
 static struct inet6_dev * ipv6_add_dev(struct net_device *dev)
 {
 	struct inet6_dev *ndev;
+	struct in6_addr maddr;
 
 	ASSERT_RTNL();
 
@@ -425,6 +426,11 @@
 #endif
 	/* protected by rtnl_lock */
 	rcu_assign_pointer(dev->ip6_ptr, ndev);
+
+	/* Join all-node multicast group */
+	ipv6_addr_all_nodes(&maddr);
+	ipv6_dev_mc_inc(dev, &maddr);
+
 	return ndev;
 }