[PATCH AUTOSEL 4.9 20/33] HID: holtek: test for sanity of intfdata

[Sasha Levin]

From: Oliver Neukum <oneukum@xxxxxxxx>

[ Upstream commit 01ec0a5f19c8c82960a07f6c7410fc9e01d7fb51 ]

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: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/hid/hid-holtek-kbd.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-holtek-kbd.c b/drivers/hid/hid-holtek-kbd.c
index 6e1a4a4fc0c10..ab9da597106fa 100644
--- 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 input_dev *dev, unsigned int type,
 
 	/* 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,
-- 
2.20.1