USB: cdc-wdm: fix wdm_find_device* return value

A logic error made the wdm_find_device* functions
return a bogus pointer into static data instead of
the intended NULL no matching device was found.

Cc: stable <stable@vger.kernel.org> # v3.4+
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/class/cdc-wdm.c

@@ -109,25 +109,29 @@ static struct usb_driver wdm_driver;
 /* return intfdata if we own the interface, else look up intf in the list */
 static struct wdm_device *wdm_find_device(struct usb_interface *intf)
 {
-	struct wdm_device *desc = NULL;
+	struct wdm_device *desc;
 
 	spin_lock(&wdm_device_list_lock);
 	list_for_each_entry(desc, &wdm_device_list, device_list)
 		if (desc->intf == intf)
-			break;
+			goto found;
+	desc = NULL;
+found:
 	spin_unlock(&wdm_device_list_lock);
 
 	return desc;
 }
 
 static struct wdm_device *wdm_find_device_by_minor(int minor)
 {
-	struct wdm_device *desc = NULL;
+	struct wdm_device *desc;
 
 	spin_lock(&wdm_device_list_lock);
 	list_for_each_entry(desc, &wdm_device_list, device_list)
 		if (desc->intf->minor == minor)
-			break;
+			goto found;
+	desc = NULL;
+found:
 	spin_unlock(&wdm_device_list_lock);
 
 	return desc;