Re: [PATCH v2] net/rose: Fix to not accept on connected socket

[Kuniyuki Iwashima <kuniyu@amazon.com>]

From:   Hyunwoo Kim <v4bel@theori.io>
Date:   Mon, 23 Jan 2023 11:40:20 -0800
> If listen() and accept() are called on a rose socket
> that connect() is successful, accept() succeeds immediately.
> This is because rose_connect() queues the skb to
> sk->sk_receive_queue, and rose_accept() dequeues it.
> 
> 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>


> ---
>  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;
>  }
> -- 
> 2.25.1