USB: xhci: Don't touch xhci_td after it's freed.

On a successful transfer, urb->td is freed before the URB is ready to be
given back to the driver.  Don't touch urb->td after it's freed.  This bug
would have only shown up when xHCI debugging was turned on, and the freed
memory was quickly reused for something else.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/xhci-ring.c

@@ -1193,7 +1193,7 @@ cleanup:
 	if (urb) {
 		usb_hcd_unlink_urb_from_ep(xhci_to_hcd(xhci), urb);
 		xhci_dbg(xhci, "Giveback URB %p, len = %d, status = %d\n",
-				urb, td->urb->actual_length, status);
+				urb, urb->actual_length, status);
 		spin_unlock(&xhci->lock);
 		usb_hcd_giveback_urb(xhci_to_hcd(xhci), urb, status);
 		spin_lock(&xhci->lock);