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

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>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index c1401f43d40fc5c5a85dbcbcba424ad2e649ab56..d9d4c92e06b312e6c300afd8f3d5db33161fd9f7 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -7034,6 +7034,9 @@ 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))