1 files changed, 15 insertions, 32 deletions

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index d34588850545..f46d8f6c40aa 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -695,14 +695,6 @@ static bool subflow_hmac_valid(const struct request_sock *req,
 	return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
 }
 
-static void mptcp_force_close(struct sock *sk)
-{
-	/* the msk is not yet exposed to user-space, and refcount is 2 */
-	inet_sk_state_store(sk, TCP_CLOSE);
-	sk_common_release(sk);
-	sock_put(sk);
-}
-
 static void subflow_ulp_fallback(struct sock *sk,
 				 struct mptcp_subflow_context *old_ctx)
 {
@@ -754,7 +746,6 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 	struct mptcp_subflow_request_sock *subflow_req;
 	struct mptcp_options_received mp_opt;
 	bool fallback, fallback_is_fatal;
-	struct sock *new_msk = NULL;
 	struct mptcp_sock *owner;
 	struct sock *child;
 
@@ -783,14 +774,9 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 		 * options.
 		 */
 		mptcp_get_options(skb, &mp_opt);
-		if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
+		if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC))
 			fallback = true;
-			goto create_child;
-		}
 
-		new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req);
-		if (!new_msk)
-			fallback = true;
 	} else if (subflow_req->mp_join) {
 		mptcp_get_options(skb, &mp_opt);
 		if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ) ||
@@ -819,23 +805,23 @@ create_child:
 				subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 				goto dispose_child;
 			}
-
-			if (new_msk)
-				mptcp_copy_inaddrs(new_msk, child);
-			mptcp_subflow_drop_ctx(child);
-			goto out;
+			goto fallback;
 		}
 
 		/* ssk inherits options of listener sk */
 		ctx->setsockopt_seq = listener->setsockopt_seq;
 
 		if (ctx->mp_capable) {
-			owner = mptcp_sk(new_msk);
+			ctx->conn = mptcp_sk_clone(listener->conn, &mp_opt, req);
+			if (!ctx->conn)
+				goto fallback;
+
+			owner = mptcp_sk(ctx->conn);
 
 			/* this can't race with mptcp_close(), as the msk is
 			 * not yet exposted to user-space
 			 */
-			inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED);
+			inet_sk_state_store(ctx->conn, TCP_ESTABLISHED);
 
 			/* record the newly created socket as the first msk
 			 * subflow, but don't link it yet into conn_list
@@ -845,11 +831,9 @@ create_child:
 			/* new mpc subflow takes ownership of the newly
 			 * created mptcp socket
 			 */
-			mptcp_sk(new_msk)->setsockopt_seq = ctx->setsockopt_seq;
+			owner->setsockopt_seq = ctx->setsockopt_seq;
 			mptcp_pm_new_connection(owner, child, 1);
 			mptcp_token_accept(subflow_req, owner);
-			ctx->conn = new_msk;
-			new_msk = NULL;
 
 			/* set msk addresses early to ensure mptcp_pm_get_local_id()
 			 * uses the correct data
@@ -899,11 +883,6 @@ create_child:
 		}
 	}
 
-out:
-	/* dispose of the left over mptcp master, if any */
-	if (unlikely(new_msk))
-		mptcp_force_close(new_msk);
-
 	/* check for expected invariant - should never trigger, just help
 	 * catching eariler subtle bugs
 	 */
@@ -921,6 +900,10 @@ dispose_child:
 
 	/* The last child reference will be released by the caller */
 	return child;
+
+fallback:
+	mptcp_subflow_drop_ctx(child);
+	return child;
 }
 
 static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
@@ -1344,7 +1327,7 @@ fallback:
 			subflow->reset_reason = MPTCP_RST_EMPTCP;
 
 reset:
-			ssk->sk_err = EBADMSG;
+			WRITE_ONCE(ssk->sk_err, EBADMSG);
 			tcp_set_state(ssk, TCP_CLOSE);
 			while ((skb = skb_peek(&ssk->sk_receive_queue)))
 				sk_eat_skb(ssk, skb);
@@ -1428,7 +1411,7 @@ void __mptcp_error_report(struct sock *sk)
 		ssk_state = inet_sk_state_load(ssk);
 		if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
 			inet_sk_state_store(sk, ssk_state);
-		sk->sk_err = -err;
+		WRITE_ONCE(sk->sk_err, -err);
 
 		/* This barrier is coupled with smp_rmb() in mptcp_poll() */
 		smp_wmb();