USB HID: fix a possible NULL pointer dereference when we fail to allocate memory

If, in usb_hid_configure(), we fail to allocate storage for 'usbhid',
 "if (!(usbhid = kzalloc(sizeof(struct usbhid_device), GFP_KERNEL)))",
then we'll jump to the 'fail:' label where we have this code:
        usb_free_urb(usbhid->urbin);
        usb_free_urb(usbhid->urbout);
        usb_free_urb(usbhid->urbctrl);
Since we got here because we couldn't allocate storage for 'usbhid',
what we have here is a NULL pointer dereference - ouch...

This patch solves that little problem by adding a new
'fail_no_usbhid:' label after the problematic calls to
usb_free_urb() and jumps to that one instead, in the problem case.
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/usbhid/hid-core.c

@@ -743,7 +743,7 @@ static struct hid_device *usb_hid_configure(struct usb_interface *intf)
 	hid->quirks = quirks;
 
 	if (!(usbhid = kzalloc(sizeof(struct usbhid_device), GFP_KERNEL)))
-		goto fail;
+		goto fail_no_usbhid;
 
 	hid->driver_data = usbhid;
 	usbhid->hid = hid;
@@ -877,6 +877,7 @@ fail:
 	usb_free_urb(usbhid->urbin);
 	usb_free_urb(usbhid->urbout);
 	usb_free_urb(usbhid->urbctrl);
+fail_no_usbhid:
 	hid_free_buffers(dev, hid);
 	hid_free_device(hid);