Merge branch 'mptcp-fixes'

Florian Westphal says:

====================
mptcp: fix 'attempt to release socket in state...' splats

These two patches fix error handling corner-cases where
inet_sock_destruct gets called for a mptcp_sk that is not in TCP_CLOSE
state.  This results in unwanted error printks from the network stack.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 37 insertions, 4 deletions

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 9936e33ac351..7e816c733ccb 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1355,12 +1355,15 @@ struct sock *mptcp_sk_clone(const struct sock *sk, struct request_sock *req)
 	msk->subflow = NULL;
 
 	if (unlikely(mptcp_token_new_accept(subflow_req->token, nsk))) {
+		nsk->sk_state = TCP_CLOSE;
 		bh_unlock_sock(nsk);
 
 		/* we can't call into mptcp_close() here - possible BH context
-		 * free the sock directly
+		 * free the sock directly.
+		 * sk_clone_lock() sets nsk refcnt to two, hence call sk_free()
+		 * too.
 		 */
-		nsk->sk_prot->destroy(nsk);
+		sk_common_release(nsk);
 		sk_free(nsk);
 		return NULL;
 	}
@@ -1431,6 +1434,7 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
 		newsk = new_mptcp_sock;
 		mptcp_copy_inaddrs(newsk, ssk);
 		list_add(&subflow->node, &msk->conn_list);
+		inet_sk_state_store(newsk, TCP_ESTABLISHED);
 
 		bh_unlock_sock(new_mptcp_sock);
 
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 50a8bea987c6..bc46b5091b9d 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -347,6 +347,35 @@ static bool subflow_hmac_valid(const struct request_sock *req,
 	return ret;
 }
 
+static void mptcp_sock_destruct(struct sock *sk)
+{
+	/* if new mptcp socket isn't accepted, it is free'd
+	 * from the tcp listener sockets request queue, linked
+	 * from req->sk.  The tcp socket is released.
+	 * This calls the ULP release function which will
+	 * also remove the mptcp socket, via
+	 * sock_put(ctx->conn).
+	 *
+	 * Problem is that the mptcp socket will not be in
+	 * SYN_RECV state and doesn't have SOCK_DEAD flag.
+	 * Both result in warnings from inet_sock_destruct.
+	 */
+
+	if (sk->sk_state == TCP_SYN_RECV) {
+		sk->sk_state = TCP_CLOSE;
+		WARN_ON_ONCE(sk->sk_socket);
+		sock_orphan(sk);
+	}
+
+	inet_sock_destruct(sk);
+}
+
+static void mptcp_force_close(struct sock *sk)
+{
+	inet_sk_state_store(sk, TCP_CLOSE);
+	sk_common_release(sk);
+}
+
 static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 					  struct sk_buff *skb,
 					  struct request_sock *req,
@@ -422,7 +451,7 @@ create_child:
 			/* new mpc subflow takes ownership of the newly
 			 * created mptcp socket
 			 */
-			inet_sk_state_store(new_msk, TCP_ESTABLISHED);
+			new_msk->sk_destruct = mptcp_sock_destruct;
 			mptcp_pm_new_connection(mptcp_sk(new_msk), 1);
 			ctx->conn = new_msk;
 			new_msk = NULL;
@@ -444,7 +473,7 @@ create_child:
 out:
 	/* dispose of the left over mptcp master, if any */
 	if (unlikely(new_msk))
-		sock_put(new_msk);
+		mptcp_force_close(new_msk);
 	return child;
 
 close_child: