From f2b0b5210f67c56a3bcdf92ff665fb285d6e0067 Mon Sep 17 00:00:00 2001 From: Hyunwoo Kim Date: Mon, 23 Jan 2023 11:43:23 -0800 Subject: [PATCH] net/x25: Fix to not accept on connected socket When listen() and accept() are called on an x25 socket that connect() succeeds, accept() succeeds immediately. This is because x25_connect() queues the skb to sk->sk_receive_queue, and x25_accept() dequeues it. This creates a child socket with the sk of the parent x25 socket, which can cause confusion. Fix x25_listen() to return -EINVAL if the socket has already been successfully connect()ed to avoid this issue. Signed-off-by: Hyunwoo Kim Signed-off-by: David S. Miller --- net/x25/af_x25.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index 3b55502b2965..5c7ad301d742 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -482,6 +482,12 @@ static int x25_listen(struct socket *sock, int backlog) int rc = -EOPNOTSUPP; lock_sock(sk); + if (sock->state != SS_UNCONNECTED) { + rc = -EINVAL; + release_sock(sk); + return rc; + } + if (sk->sk_state != TCP_LISTEN) { memset(&x25_sk(sk)->dest_addr, 0, X25_ADDR_LEN); sk->sk_max_ack_backlog = backlog;