xhci: Fix list corruption in urb dequeue at host removal

xhci driver frees data for all devices, both usb2 and and usb3 the
first time usb_remove_hcd() is called, including td_list and and xhci_ring
structures.

When usb_remove_hcd() is called a second time for the second xhci bus it
will try to dequeue all pending urbs, and touches td_list which is already
freed for that endpoint.

Cc: <stable@vger.kernel.org>
Reported-by: Joe Lawrence <joe.lawrence@stratus.com>
Tested-by: Joe Lawrence <joe.lawrence@stratus.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 26a44c0..0c8087d 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1554,7 +1554,9 @@ int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
                xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
                                "HW died, freeing TD.");
                urb_priv = urb->hcpriv;
-               for (i = urb_priv->td_cnt; i < urb_priv->length; i++) {
+               for (i = urb_priv->td_cnt;
+                    i < urb_priv->length && xhci->devs[urb->dev->slot_id];
+                    i++) {
                        td = urb_priv->td[i];
                        if (!list_empty(&td->td_list))
                                list_del_init(&td->td_list);