As David Laight noticed,
"In a multithreaded program it is reasonable to have a thread blocked in
accept(). With TCP a subsequent shutdown(listen_fd, SHUT_RDWR) causes
the accept to fail. But nothing happens for SCTP."
sctp_disconnect() is eventually called when shutdown a listen socket,
but nothing is done in this function. This patch sets RCV_SHUTDOWN
flag in sk->sk_shutdown there, and adds the check (sk->sk_shutdown &
RCV_SHUTDOWN) to break and return in sctp_accept().
Note that shutdown() is only supported on TCP-style SCTP socket.
Reported-by: David Laight <David.Laight@xxxxxxxxxx>
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
---
net/sctp/socket.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index c67679a41044..da299455cd10 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4834,10 +4834,14 @@ int sctp_inet_connect(struct socket *sock, struct sockaddr *uaddr,
return sctp_connect(sock->sk, uaddr, addr_len, flags);
}
-/* FIXME: Write comments. */
+/* Only called when shutdown a listening SCTP socket. */
static int sctp_disconnect(struct sock *sk, int flags)
{
- return -EOPNOTSUPP; /* STUB */
+ if (!sctp_style(sk, TCP))
+ return -EOPNOTSUPP;
+
+ sk->sk_shutdown |= RCV_SHUTDOWN;
+ return 0;
}
/* 4.1.4 accept() - TCP Style Syntax
@@ -4866,7 +4870,8 @@ static struct sock *sctp_accept(struct sock *sk, int flags, int *err, bool kern)
goto out;
}
- if (!sctp_sstate(sk, LISTENING)) {
+ if (!sctp_sstate(sk, LISTENING) ||
+ (sk->sk_shutdown & RCV_SHUTDOWN)) {
error = -EINVAL;
goto out;
}
@@ -9392,7 +9397,8 @@ static int sctp_wait_for_accept(struct sock *sk, long timeo)
}
err = -EINVAL;
- if (!sctp_sstate(sk, LISTENING))
+ if (!sctp_sstate(sk, LISTENING) ||
+ (sk->sk_shutdown & RCV_SHUTDOWN))
break;
err = 0;
--
2.43.0
