HID: bigbenff: prevent null pointer dereference

When emulating the device through uhid, there is a chance we don't have
output reports and so report_field is null.

Cc: [email protected]
Signed-off-by: Benjamin Tissoires <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: bentiss

drivers/hid/hid-bigbenff.c

@@ -191,7 +191,7 @@ static void bigben_worker(struct work_struct *work)
 		struct bigben_device, worker);
 	struct hid_field *report_field = bigben->report->field[0];
 
-	if (bigben->removed)
+	if (bigben->removed || !report_field)
 		return;
 
 	if (bigben->work_led) {