sctp: listen on the sock only when it's state is listening or closed

[ Upstream commit 34b2789f1d9bf8dcca9b5cb553d076ca2cd898ee ]

Now sctp doesn't check sock's state before listening on it. It could
even cause changing a sock with any state to become a listening sock
when doing sctp_listen.

This patch is to fix it by checking sock's state in sctp_listen, so
that it will listen on the sock with right state.

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 3c5833058b0368674e21e0c57bb82dba0ff5a7a6..faecab3bdf64cab133587ee1eaa81993bb04e47e 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -6395,6 +6395,9 @@ int sctp_inet_listen(struct socket *sock, int backlog)
        if (sock->state != SS_UNCONNECTED)
                goto out;
 
+       if (!sctp_sstate(sk, LISTENING) && !sctp_sstate(sk, CLOSED))
+               goto out;
+
        /* If backlog is zero, disable listening. */
        if (!backlog) {
                if (sctp_sstate(sk, CLOSED))