tcp: tracepoint: only call trace_tcp_send_reset with full socket

tracepoint tcp_send_reset requires a full socket to work. However, it
may be called when in TCP_TIME_WAIT:

        case TCP_TW_RST:
                tcp_v6_send_reset(sk, skb);
                inet_twsk_deschedule_put(inet_twsk(sk));
                goto discard_it;

To avoid this problem, this patch checks the socket with sk_fullsock()
before calling trace_tcp_send_reset().

Fixes: c24b14c46bb8 ("tcp: add tracepoint trace_tcp_send_reset")
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 95738aa0d8a6..f8ad397e285e 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -705,7 +705,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
          */
         if (sk) {
                 arg.bound_dev_if = sk->sk_bound_dev_if;
-                trace_tcp_send_reset(sk, skb);
+                if (sk_fullsock(sk))
+                        trace_tcp_send_reset(sk, skb);
         }
 
         BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) !=