Disallow listen() on sockets which are in the SS_ISCONNECTED or

SS_ISCONNECTING state, returning EINVAL (which is what POSIX mandates
in this case).
listen() on connected or connecting sockets would cause them to enter
a bad state; in the TCP case, this could cause sockets to go
catatonic or panics, depending on how the socket was connected.

Reviewed by:	-net
MFC after:	2 weeks

1 files changed, 4 insertions, 0 deletions

diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index c4d596f..4163f2e 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -266,6 +266,10 @@ solisten(so, backlog, td)
 	int s, error;
 
 	s = splnet();
+	if (so->so_state & (SS_ISCONNECTED | SS_ISCONNECTING)) {
+		splx(s);
+		return (EINVAL);
+	}
 	error = (*so->so_proto->pr_usrreqs->pru_listen)(so, td);
 	if (error) {
 		splx(s);