[PATCH 4.14 14/71] HID: holtek: test for sanity of intfdata

[Greg Kroah-Hartman]

From: Oliver Neukum <oneukum@xxxxxxxx>

commit 01ec0a5f19c8c82960a07f6c7410fc9e01d7fb51 upstream.

The ioctl handler uses the intfdata of a second interface,
which may not be present in a broken or malicious device, hence
the intfdata needs to be checked for NULL.

[jkosina@xxxxxxx: fix newly added spurious space]
Reported-by: syzbot+965152643a75a56737be@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/hid/hid-holtek-kbd.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/drivers/hid/hid-holtek-kbd.c
+++ b/drivers/hid/hid-holtek-kbd.c
@@ -126,9 +126,14 @@ static int holtek_kbd_input_event(struct
 
 	/* Locate the boot interface, to receive the LED change events */
 	struct usb_interface *boot_interface = usb_ifnum_to_if(usb_dev, 0);
+	struct hid_device *boot_hid;
+	struct hid_input *boot_hid_input;
 
-	struct hid_device *boot_hid = usb_get_intfdata(boot_interface);
-	struct hid_input *boot_hid_input = list_first_entry(&boot_hid->inputs,
+	if (unlikely(boot_interface == NULL))
+		return -ENODEV;
+
+	boot_hid = usb_get_intfdata(boot_interface);
+	boot_hid_input = list_first_entry(&boot_hid->inputs,
 		struct hid_input, list);
 
 	return boot_hid_input->input->event(boot_hid_input->input, type, code,