xhci: fix null pointer dereference in stop command timeout function

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
hcd.

CC: <stable@vger.kernel.org>
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-ring.c b/drivers/usb/host/xhci-ring.c
index fd9fd12..797137e 100644 (file)
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -850,6 +850,10 @@ void xhci_stop_endpoint_command_watchdog(unsigned long arg)
        spin_lock_irqsave(&xhci->lock, flags);
 
        ep->stop_cmds_pending--;
+       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 "
@@ -903,7 +907,7 @@ void xhci_stop_endpoint_command_watchdog(unsigned long arg)
        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.");
 }