[PATCH 3.12 130/142] xhci: Fix list corruption in urb dequeue at host removal

From: Jiri Slaby
Date: Wed Feb 24 2016 - 05:15:00 EST

From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.


commit 5c82171167adb8e4ac77b91a42cd49fb211a81a0 upstream.

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

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.

Reported-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
Tested-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
drivers/usb/host/xhci.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index dfcf0a3527b8..806ed2ba1c6e 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1522,7 +1522,9 @@ 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))