USB: serial: keyspan: handle unbound ports

Check for NULL port data in the control URB completion handlers to avoid
dereferencing a NULL pointer in the unlikely case where a port device
isn't bound to a driver (e.g. after an allocation failure on port
probe()).

Fixes: 0ca1268e ("USB Serial Keyspan: add support for USA-49WG & USA-28XG")
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/keyspan.c

@@ -1058,6 +1058,8 @@ static void	usa49_glocont_callback(struct urb *urb)
 	for (i = 0; i < serial->num_ports; ++i) {
 		port = serial->port[i];
 		p_priv = usb_get_serial_port_data(port);
+		if (!p_priv)
+			continue;
 
 		if (p_priv->resend_cont) {
 			dev_dbg(&port->dev, "%s - sending setup\n", __func__);
@@ -1459,6 +1461,8 @@ static void usa67_glocont_callback(struct urb *urb)
 	for (i = 0; i < serial->num_ports; ++i) {
 		port = serial->port[i];
 		p_priv = usb_get_serial_port_data(port);
+		if (!p_priv)
+			continue;
 
 		if (p_priv->resend_cont) {
 			dev_dbg(&port->dev, "%s - sending setup\n", __func__);