ipv4: fix ip_send_skb()

ip_send_skb() can send orphaned skb, so we must pass the net pointer to
avoid possible NULL dereference in error path.

Bug added by commit 3a7c384ffd57 (ipv4: tcp: unicast_sock should not
land outside of TCP stack)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip.h b/include/net/ip.h
index bd5e444a..5a5d84d 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -120,7 +120,7 @@
 				      struct flowi4 *fl4,
 				      struct sk_buff_head *queue,
 				      struct inet_cork *cork);
-extern int		ip_send_skb(struct sk_buff *skb);
+extern int		ip_send_skb(struct net *net, struct sk_buff *skb);
 extern int		ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4);
 extern void		ip_flush_pending_frames(struct sock *sk);
 extern struct sk_buff  *ip_make_skb(struct sock *sk,