patch "xhci: fix null pointer dereference in stop command timeout function" added to usb-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    xhci: fix null pointer dereference in stop command timeout function

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From bcf42aa60c2832510b9be0f30c090bfd35bb172d Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@linux.intel.com>
Date: Wed, 7 Sep 2016 17:26:33 +0300
Subject: 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>
---
 drivers/usb/host/xhci-ring.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index fd9fd12e4861..797137e26549 100644
--- 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.");
 }
-- 
2.9.3