[PATCH v3 2/3] HID: wacom: fix problems when device is not a valid USB device

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

The wacom driver accepts devices of more than just USB types, but some
code paths can cause problems if the device being controlled is not a
USB device due to a lack of checking.  Add the needed checks to ensure
that the USB device accesses are only happening on a "real" USB device,
and not one on some other bus.

Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: linux-input@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
v3: no change
v2: split into separate patch
    refined test to not abort probe for any non-USB device as the driver
    works for many other types based on Benjamin's review

 drivers/hid/wacom_sys.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
index 22d73772fbc5..066c567dbaa2 100644
--- a/drivers/hid/wacom_sys.c
+++ b/drivers/hid/wacom_sys.c
@@ -726,7 +726,7 @@ static void wacom_retrieve_hid_descriptor(struct hid_device *hdev,
 	 * Skip the query for this type and modify defaults based on
 	 * interface number.
 	 */
-	if (features->type == WIRELESS) {
+	if (features->type == WIRELESS && intf) {
 		if (intf->cur_altsetting->desc.bInterfaceNumber == 0)
 			features->device_type = WACOM_DEVICETYPE_WL_MONITOR;
 		else
@@ -2451,6 +2451,9 @@ static void wacom_wireless_work(struct work_struct *work)
 
 	wacom_destroy_battery(wacom);
 
+	if (!usbdev)
+		return;
+
 	/* Stylus interface */
 	hdev1 = usb_get_intfdata(usbdev->config->interface[1]);
 	wacom1 = hid_get_drvdata(hdev1);
@@ -2730,8 +2733,6 @@ static void wacom_mode_change_work(struct work_struct *work)
 static int wacom_probe(struct hid_device *hdev,
 		const struct hid_device_id *id)
 {
-	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
-	struct usb_device *dev = interface_to_usbdev(intf);
 	struct wacom *wacom;
 	struct wacom_wac *wacom_wac;
 	struct wacom_features *features;
@@ -2766,8 +2767,14 @@ static int wacom_probe(struct hid_device *hdev,
 	wacom_wac->hid_data.inputmode = -1;
 	wacom_wac->mode_report = -1;
 
-	wacom->usbdev = dev;
-	wacom->intf = intf;
+	if (hid_is_usb(hdev)) {
+		struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+		struct usb_device *dev = interface_to_usbdev(intf);
+
+		wacom->usbdev = dev;
+		wacom->intf = intf;
+	}
+
 	mutex_init(&wacom->lock);
 	INIT_DELAYED_WORK(&wacom->init_work, wacom_init_work);
 	INIT_WORK(&wacom->wireless_work, wacom_wireless_work);
-- 
2.34.1