FAILED: patch "[PATCH] net/smc: fix connection leak" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9f1c50cf39167ff71dc5953a3234f3f6eeb8fcb5 Mon Sep 17 00:00:00 2001
From: "D. Wythe" <[email protected]>
Date: Thu, 24 Feb 2022 23:26:19 +0800
Subject: [PATCH] net/smc: fix connection leak

There's a potential leak issue under following execution sequence :

smc_release smc_connect_work
if (sk->sk_state == SMC_INIT)

					send_clc_confirim
	tcp_abort();
					...
					sk.sk_state = SMC_ACTIVE

smc_close_active
switch(sk->sk_state) {
...
case SMC_ACTIVE:

	smc_close_final()
	// then wait peer closed

Unfortunately, tcp_abort() may discard CLC CONFIRM messages that are still in the tcp send buffer, in which case our connection token cannot be delivered to the server side, which means that we cannot get a passive close message at all. Therefore, it is impossible for the to be disconnected at all.

This patch tries a very simple way to avoid this issue, once the state has changed to SMC_ACTIVE after tcp_abort(), we can actively abort the smc connection, considering that the state is SMC_INIT before tcp_abort(), abandoning the complete disconnection process should not cause too much problem.

In fact, this problem may exist as long as the CLC CONFIRM message is not received by the server. Whether a timer should be added after smc_close_final() needs to be discussed in the future. But even so, this patch provides a faster release for connection in above case, it should also be valuable.

index 306d9e8cd1dd..81984c1c0e78 100644
@@ -183,7 +183,7 @@ static int smc_release(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
 	struct smc_sock *smc;
-	int rc = 0;
+	int old_state, rc = 0;
 
 	if (!sk)
 		goto out;

@@ -191,8 +191,10 @@ static int smc_release(struct socket *sock)
 	sock_hold(sk); /* sock_put below */
 	smc = smc_sk(sk);
 
+	old_state = sk->sk_state;
+
 	/* cleanup for a dangling non-blocking connect */
-	if (smc->connect_nonblock && sk->sk_state == SMC_INIT)
+	if (smc->connect_nonblock && old_state == SMC_INIT)
 		tcp_abort(smc->clcsock->sk, ECONNABORTED);
 
 	if (cancel_work_sync(&smc->connect_work))

@@ -206,6 +208,10 @@ static int smc_release(struct socket *sock)
 	else
 		lock_sock(sk);
 
+	if (old_state == SMC_INIT && sk->sk_state == SMC_ACTIVE &&
+	    !smc->use_fallback)
+		smc_close_active_abort(smc);
+
 	rc = __smc_release(smc);
 
 	/* detach socket */