ttyprintk: Fix NULL pointer deref by setting tty_port ops after initializing port

tty_port_init() zeroes out the tty port, which means that we have to set the
ops pointer /after/, not before this call.  Otherwise, tty_port_open will crash
when it tries to deref ops, which is now a NULL pointer.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/ttyprintk.c

@@ -179,7 +179,6 @@ static int __init ttyprintk_init(void)
 {
 	int ret = -ENOMEM;
 
-	tpk_port.port.ops = &null_ops;
 	mutex_init(&tpk_port.port_write_mutex);
 
 	ttyprintk_driver = tty_alloc_driver(1,
@@ -190,6 +189,7 @@ static int __init ttyprintk_init(void)
 		return PTR_ERR(ttyprintk_driver);
 
 	tty_port_init(&tpk_port.port);
+	tpk_port.port.ops = &null_ops;
 
 	ttyprintk_driver->driver_name = "ttyprintk";
 	ttyprintk_driver->name = "ttyprintk";