[PATCH net] tcp: tracepoint: only call trace_tcp_send_reset with full socket

[PATCH net] tcp: tracepoint: only call trace_tcp_send_reset with full socket

[Song Liu]

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>
---
 net/ipv4/tcp_ipv4.c | 3 ++-
 net/ipv6/tcp_ipv6.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 95738aa..f8ad397 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) !=
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index a1ab29e..412139f 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -942,7 +942,8 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
 
 	if (sk) {
 		oif = sk->sk_bound_dev_if;
-		trace_tcp_send_reset(sk, skb);
+		if (sk_fullsock(sk))
+			trace_tcp_send_reset(sk, skb);
 	}
 
 	tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1, 0, 0);
-- 
2.9.5

Re: [PATCH net] tcp: tracepoint: only call trace_tcp_send_reset with full socket

[David Miller]

From: Song Liu <songliubraving@fb.com>
Date: Tue, 6 Feb 2018 20:50:23 -0800

> 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>

Applied and queued up for -stable, thank you.