ipv6: remove old token ipv6 address as soon as possible

If the tokenized ip address is re-set on an interface we depend on the
arrival of a new router advertisment to call addrconf_verify to clean
up the old address (which valid_lft is now set to 0). Old addresses can
linger around for a longer time if e.g. the source of router advertisments
vanishes.

So, call addrconf_verify immediately after setting the new tokenized
address to get rid of the old tokenized addresses.

Cc: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -4375,6 +4375,7 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token)
 	}
 
 	write_unlock_bh(&idev->lock);
+	addrconf_verify(0);
 	return 0;
 }