Patch "xhci: fix null pointer dereference in stop command timeout function" has been added to the 4.7-stable tree

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 the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xhci-fix-null-pointer-dereference-in-stop-command-timeout-function.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mathias Nyman <[email protected]>
Date: Wed, 7 Sep 2016 17:26:33 +0300
Subject: xhci: fix null pointer dereference in stop command timeout function

From: Mathias Nyman <[email protected]>

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 hcd.

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

@@ -840,6 +840,10 @@ void xhci_stop_endpoint_command_watchdog
 	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 "

@@ -893,7 +897,7 @@ 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.");
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/xhci-fix-null-pointer-dereference-in-stop-command-timeout-function.patch