From 14caefcf9837a2be765a566005ad82cd0d2a429f Mon Sep 17 00:00:00 2001
From: Hyunwoo Kim <v4bel@theori.io>
Date: Wed, 25 Jan 2023 02:59:44 -0800
Subject: [PATCH] net/rose: Fix to not accept on connected socket
Git-commit: 14caefcf9837a2be765a566005ad82cd0d2a429f
Patch-mainline: v6.2-rc7
References: git-fixes

If you call listen() and accept() on an already connect()ed
rose socket, accept() can successfully connect.
This is because when the peer socket sends data to sendmsg,
the skb with its own sk stored in the connected socket's
sk->sk_receive_queue is connected, and rose_accept() dequeues
the skb waiting in the sk->sk_receive_queue.

This creates a child socket with the sk of the parent
rose socket, which can cause confusion.

Fix rose_listen() to return -EINVAL if the socket has
already been successfully connected, and add lock_sock
to prevent this issue.

Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230125105944.GA133314@ubuntu
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/rose/af_rose.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c
index 36fefc3957d7..ca2b17f32670 100644
--- a/net/rose/af_rose.c
+++ b/net/rose/af_rose.c
@@ -488,6 +488,12 @@ static int rose_listen(struct socket *sock, int backlog)
 {
 	struct sock *sk = sock->sk;
 
+	lock_sock(sk);
+	if (sock->state != SS_UNCONNECTED) {
+		release_sock(sk);
+		return -EINVAL;
+	}
+
 	if (sk->sk_state != TCP_LISTEN) {
 		struct rose_sock *rose = rose_sk(sk);
 
@@ -497,8 +503,10 @@ static int rose_listen(struct socket *sock, int backlog)
 		memset(rose->dest_digis, 0, AX25_ADDR_LEN * ROSE_MAX_DIGIS);
 		sk->sk_max_ack_backlog = backlog;
 		sk->sk_state           = TCP_LISTEN;
+		release_sock(sk);
 		return 0;
 	}
+	release_sock(sk);
 
 	return -EOPNOTSUPP;
 }
-- 
2.35.3