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>

3 files changed, 4 insertions, 5 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index bd5e444a19ce..5a5d84d3d2c6 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -120,7 +120,7 @@ extern struct sk_buff  *__ip_make_skb(struct sock *sk,
                                       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,
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index ec410e08b4b9..147ccc3e93db 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1366,9 +1366,8 @@ out:
         return skb;
 }
 
-int ip_send_skb(struct sk_buff *skb)
+int ip_send_skb(struct net *net, struct sk_buff *skb)
 {
-        struct net *net = sock_net(skb->sk);
         int err;
 
         err = ip_local_out(skb);
@@ -1391,7 +1390,7 @@ int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
                 return 0;
 
         /* Netfilter gets whole the not fragmented skb. */
-        return ip_send_skb(skb);
+        return ip_send_skb(sock_net(sk), skb);
 }
 
 /*
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b4c3582a991f..6f6d1aca3c3d 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -758,7 +758,7 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4)
                 uh->check = CSUM_MANGLED_0;
 
 send:
-        err = ip_send_skb(skb);
+        err = ip_send_skb(sock_net(sk), skb);
         if (err) {
                 if (err == -ENOBUFS && !inet->recverr) {
                         UDP_INC_STATS_USER(sock_net(sk),