netns: Add network namespace argument to rt6_fill_node() and ipv6_dev_get_saddr()

ipv6_dev_get_saddr() blindly de-references dst_dev to get the network
namespace, but some callers might pass NULL.  Change callers to pass a
namespace pointer instead.

Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index 483a01d..47f91af 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -319,7 +319,8 @@
 			  __func__, asoc, dst, NIP6(daddr->v6.sin6_addr));
 
 	if (!asoc) {
-		ipv6_dev_get_saddr(dst ? ip6_dst_idev(dst)->dev : NULL,
+		ipv6_dev_get_saddr(sock_net(sctp_opt2sk(sk)),
+				   dst ? ip6_dst_idev(dst)->dev : NULL,
 				   &daddr->v6.sin6_addr,
 				   inet6_sk(&sk->inet.sk)->srcprefs,
 				   &saddr->v6.sin6_addr);