USB: keyspan: fix NULL-pointer dereferences and memory leaks

Fix NULL-pointer dereference at release by moving port data allocation
and deallocation to port_probe and port_remove.

Fix NULL-pointer dereference at disconnect by stopping port urbs at
port_remove.

Since commit 0998d0631001288 (device-core: Ensure drvdata = NULL when no
driver is bound) the port private data is no longer accessible at
disconnect or release.

Note that this patch also fixes port and interface-data memory leaks in
the error path of attach should port initialisation fail for any port.

Compile-only tested.

Cc: <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/serial/keyspan.h b/drivers/usb/serial/keyspan.h
index 0a8a40b..0273dda 100644
--- a/drivers/usb/serial/keyspan.h
+++ b/drivers/usb/serial/keyspan.h
@@ -42,6 +42,8 @@
 static int  keyspan_startup		(struct usb_serial *serial);
 static void keyspan_disconnect		(struct usb_serial *serial);
 static void keyspan_release		(struct usb_serial *serial);
+static int keyspan_port_probe(struct usb_serial_port *port);
+static int keyspan_port_remove(struct usb_serial_port *port);
 static int  keyspan_write_room		(struct tty_struct *tty);
 
 static int  keyspan_write		(struct tty_struct *tty,
@@ -567,6 +569,8 @@
 	.attach			= keyspan_startup,
 	.disconnect		= keyspan_disconnect,
 	.release		= keyspan_release,
+	.port_probe		= keyspan_port_probe,
+	.port_remove		= keyspan_port_remove,
 };
 
 static struct usb_serial_driver keyspan_2port_device = {
@@ -589,6 +593,8 @@
 	.attach			= keyspan_startup,
 	.disconnect		= keyspan_disconnect,
 	.release		= keyspan_release,
+	.port_probe		= keyspan_port_probe,
+	.port_remove		= keyspan_port_remove,
 };
 
 static struct usb_serial_driver keyspan_4port_device = {
@@ -611,6 +617,8 @@
 	.attach			= keyspan_startup,
 	.disconnect		= keyspan_disconnect,
 	.release		= keyspan_release,
+	.port_probe		= keyspan_port_probe,
+	.port_remove		= keyspan_port_remove,
 };
 
 static struct usb_serial_driver * const serial_drivers[] = {