[PATCH 4.4 070/118] xhci: fix null pointer dereference in stop command timeout function

From: Greg Kroah-Hartman
Date: Thu Sep 22 2016 - 15:05:26 EST

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


From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

commit bcf42aa60c2832510b9be0f30c090bfd35bb172d upstream.

The stop endpoint command has its own 5 second timeout timer.
If the timeout function is triggered between USB3 and USB2 host
removal it will try to call usb_hc_died(xhci_to_hcd(xhci)->primary_hcd)

the ->primary_hcd will be set to NULL at USB3 hcd removal.

Fix this by first checking if the PCI host is being removed, and
also by using only xhci_to_hcd() as it will always return the primary

Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/usb/host/xhci-ring.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -846,6 +846,10 @@ void xhci_stop_endpoint_command_watchdog
spin_lock_irqsave(&xhci->lock, flags);

+ if (xhci->xhc_state & XHCI_STATE_REMOVING) {
+ spin_unlock_irqrestore(&xhci->lock, flags);
+ return;
+ }
if (xhci->xhc_state & XHCI_STATE_DYING) {
xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
"Stop EP timer ran, but another timer marked "
@@ -899,7 +903,7 @@ void xhci_stop_endpoint_command_watchdog
spin_unlock_irqrestore(&xhci->lock, flags);
xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
"Calling usb_hc_died()");
- usb_hc_died(xhci_to_hcd(xhci)->primary_hcd);
+ usb_hc_died(xhci_to_hcd(xhci));
xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
"xHCI host controller is dead.");