Input: xpad - fix oops when attaching an unknown Xbox One gamepad

Xbox One controllers have multiple interfaces which all have the same class, subclass, and protocol. One of the these interfaces has only a single endpoint. When Xpad attempts to bind to this interface, it causes an oops when trying initialize the output URB by trying to access the second endpoint's descriptor.

This situation was avoided for known Xbox One devices by checking the XTYPE constant associated with the VID and PID tuple. However, this breaks when new or previously unknown Xbox One controllers are attached to the system.

This change addresses the problem by deriving the XTYPE for Xbox One controllers based on the interface protocol before checking the interface number.

Fixes 1a48ff81b391 ("Input: xpad - add support for Xbox One controllers")

Signed-off-by Cameron Gutman <[email protected]>

Cc [email protected]

---
This bug affects kernels since 3.18. Controllers upgraded to the 2015 firmware will trigger the oops on affected kernels (up to 4.4 when the new device ID was added). The Xbox One Elite controller will likely also trigger the oops up to 4.6 (though I've not tested myself) along with any new third-party Xbox One controllers that are released.

There are a few ways we could address it, but this one seems nice because it allows the controller to work correctly (as opposed to simply kicking out interfaces without enough endpoints).

---
 drivers/input/joystick/xpad.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

drivers/input/joystick/xpad.c +13 -10

index 923c572..3438e98 100644
@@ -1437,16 +1437,6 @@ static int xpad_probe(struct usb_interface *intf, const struct usb_device_id *id
 			break;
 	}
 
-	if (xpad_device[i].xtype == XTYPE_XBOXONE &&
-	    intf->cur_altsetting->desc.bInterfaceNumber != 0) {
-		/*
-		 * The Xbox One controller lists three interfaces all with the
-		 * same interface class, subclass and protocol. Differentiate by
-		 * interface number.
-		 */
-		return -ENODEV;
-	}
-
 	xpad = kzalloc(sizeof(struct usb_xpad), GFP_KERNEL);
 	if (!xpad)
 		return -ENOMEM;

@@ -1478,6 +1468,8 @@ static int xpad_probe(struct usb_interface *intf, const struct usb_device_id *id
 		if (intf->cur_altsetting->desc.bInterfaceClass == USB_CLASS_VENDOR_SPEC) {
 			if (intf->cur_altsetting->desc.bInterfaceProtocol == 129)
 				xpad->xtype = XTYPE_XBOX360W;
+			else if (intf->cur_altsetting->desc.bInterfaceProtocol == 208)
+				xpad->xtype = XTYPE_XBOXONE;
 			else
 				xpad->xtype = XTYPE_XBOX360;
 		} else {

@@ -1492,6 +1484,17 @@ static int xpad_probe(struct usb_interface *intf, const struct usb_device_id *id
 			xpad->mapping |= MAP_STICKS_TO_NULL;
 	}
 
+	if (xpad->xtype == XTYPE_XBOXONE &&
+	    intf->cur_altsetting->desc.bInterfaceNumber != 0) {
+		/*
+		 * The Xbox One controller lists three interfaces all with the
+		 * same interface class, subclass and protocol. Differentiate by
+		 * interface number.
+		 */
+		error = -ENODEV;
+		goto err_free_in_urb;
+	}
+
 	error = xpad_init_output(intf, xpad);
 	if (error)
 		goto err_free_in_urb;

Signature · 1 line

2.7.4

But I think it would be even better if we still validated the number of endpoints afterwards so that a device with malicious descriptors would not crash the kernel. Any chance you could make such a patch?

Thanks!