ipv4: dst_entry leak in ip_send_unicast_reply()

ip_setup_cork() called inside ip_append_data() steals dst entry from rt to cork
and in case errors in __ip_append_data() nobody frees stolen dst entry

Fixes: 2e77d89b2fa8 ("net: avoid a pair of dst_hold()/dst_release() in ip_append_data()")
Signed-off-by: Vasily Averin <vvs@parallels.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 3 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index e35b71289156..88e5ef2c7f51 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1535,6 +1535,7 @@ void ip_send_unicast_reply(struct net *net, struct sk_buff *skb,
         struct sk_buff *nskb;
         struct sock *sk;
         struct inet_sock *inet;
+        int err;
 
         if (__ip_options_echo(&replyopts.opt.opt, skb, sopt))
                 return;
@@ -1574,8 +1575,13 @@ void ip_send_unicast_reply(struct net *net, struct sk_buff *skb,
         sock_net_set(sk, net);
         __skb_queue_head_init(&sk->sk_write_queue);
         sk->sk_sndbuf = sysctl_wmem_default;
-        ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
-                       &ipc, &rt, MSG_DONTWAIT);
+        err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
+                             len, 0, &ipc, &rt, MSG_DONTWAIT);
+        if (unlikely(err)) {
+                ip_flush_pending_frames(sk);
+                goto out;
+        }
+
         nskb = skb_peek(&sk->sk_write_queue);
         if (nskb) {
                 if (arg->csumoffset >= 0)
@@ -1587,7 +1593,7 @@ void ip_send_unicast_reply(struct net *net, struct sk_buff *skb,
                 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
                 ip_push_pending_frames(sk, &fl4);
         }
-
+out:
         put_cpu_var(unicast_sock);
 
         ip_rt_put(rt);