FAILED: patch "[PATCH] mptcp: fix locking for setsockopt corner-case" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-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]>.

Possible dependencies:

21e43569685d ("mptcp: fix locking for setsockopt corner-case") d3d429047cc6 ("mptcp: sockopt: make 'tcp_fastopen_connect' generic")

thanks,

greg k-h

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

From 21e43569685de4ad773fb060c11a15f3fd5e7ac4 Mon Sep 17 00:00:00 2001
From: Paolo Abeni <[email protected]>
Date: Tue, 7 Feb 2023 14:04:14 +0100
Subject: [PATCH] mptcp: fix locking for setsockopt corner-case

We need to call the __mptcp_nmpc_socket(), and later subflow socket access under the msk socket lock, or e.g. a racing connect() could change the socket status under the hood, with unexpected results.

index d4b1e6ec1b36..7f2c3727ab23 100644
@@ -760,14 +760,21 @@ static int mptcp_setsockopt_v4(struct mptcp_sock *msk, int optname,
 static int mptcp_setsockopt_first_sf_only(struct mptcp_sock *msk, int level, int optname,
 					  sockptr_t optval, unsigned int optlen)
 {
+	struct sock *sk = (struct sock *)msk;
 	struct socket *sock;
+	int ret = -EINVAL;
 
 	/* Limit to first subflow, before the connection establishment */
+	lock_sock(sk);
 	sock = __mptcp_nmpc_socket(msk);
 	if (!sock)
-		return -EINVAL;
+		goto unlock;
 
-	return tcp_setsockopt(sock->sk, level, optname, optval, optlen);
+	ret = tcp_setsockopt(sock->sk, level, optname, optval, optlen);
+
+unlock:
+	release_sock(sk);
+	return ret;
 }
 
 static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname,