[PATCH] HID: wacom: Prevent NULL dereference in wireless work

wacom_wireless_work() assumes that the active USB configuration has
three interfaces and unconditionally accesses interface[1] and
interface[2].

A malformed configuration with fewer interfaces can therefore cause a
NULL pointer dereference in the wireless workqueue. Return early unless
the configuration has at least three interfaces.

Reported-by: Indrath <redacted>
Signed-off-by: Devarjya Purkayastha <redacted>
---
 drivers/hid/wacom_sys.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
index 628372ab818a..dcf2811a5c48 100644
--- a/drivers/hid/wacom_sys.c
+++ b/drivers/hid/wacom_sys.c

@@ -2619,7 +2619,7 @@ static void wacom_wireless_work(struct work_struct *work)
 
 	wacom_destroy_battery(wacom);
 
-	if (!usbdev)
+	if (!usbdev || usbdev->config->desc.bNumInterfaces < 3)
 		return;
 
 	/* Stylus interface */

-- 
2.53.0