USB: cdc-acm: check for valid interfaces

commit 403dff4e upstream.

We need to check that we have both a valid data and control inteface for both
types of headers (union and not union.)

References: https://bugzilla.kernel.org/show_bug.cgi?id=83551Reported-by: Simon Schubert <2+kernel@0x2c.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/usb/class/cdc-acm.c

@@ -1192,11 +1192,12 @@ static int acm_probe(struct usb_interface *intf,
 	} else {
 		control_interface = usb_ifnum_to_if(usb_dev, union_header->bMasterInterface0);
 		data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = union_header->bSlaveInterface0));
+	}
+
 	if (!control_interface || !data_interface) {
 		dev_dbg(&intf->dev, "no interfaces\n");
 		return -ENODEV;
 	}
-	}
 
 	if (data_interface_num != call_interface_num)
 		dev_dbg(&intf->dev, "Separate call control interface. That is not fully supported.\n");