HID: holtek: fix slab-out-of-bounds Write in holtek_kbd_input_event

There is a slab-out-of-bounds Write bug in hid-holtek-kbd driver.
The problem is the driver assumes the device must have an input
but some malicious devices violate this assumption.

Fix this by checking hid_device's input is non-empty before its usage.

Signed-off-by: Ma Ke <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>

Author: Ma Ke

drivers/hid/hid-holtek-kbd.c

@@ -130,6 +130,10 @@ static int holtek_kbd_input_event(struct input_dev *dev, unsigned int type,
 		return -ENODEV;
 
 	boot_hid = usb_get_intfdata(boot_interface);
+	if (list_empty(&boot_hid->inputs)) {
+		hid_err(hid, "no inputs found\n");
+		return -ENODEV;
+	}
 	boot_hid_input = list_first_entry(&boot_hid->inputs,
 		struct hid_input, list);