[PATCH 4.14 126/126] xhci: handle port status events for removed USB3 hcd

[Greg Kroah-Hartman]

From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

commit 1245374e9b8340fc255fd51b2015173a83050d03 upstream.

At xhci removal the USB3 hcd (shared_hcd) is removed before the primary
USB2 hcd. Interrupts for port status changes may still occur for USB3
ports after the shared_hcd is freed, causing  NULL pointer dereference.

Check if xhci->shared_hcd is still valid before handing USB3 port events

Cc: <stable@xxxxxxxxxxxxxxx>
Reported-by: Peter Chen <peter.chen@xxxxxxx>
Tested-by: Jack Pham <jackp@xxxxxxxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Cc: Macpaul Lin <macpaul.lin@xxxxxxxxxxxx>
[redone for 4.14.y based on Mathias's comments]
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1640,6 +1640,12 @@ static void handle_port_status(struct xh
 	if ((major_revision == 0x03) != (hcd->speed >= HCD_USB3))
 		hcd = xhci->shared_hcd;
 
+	if (!hcd) {
+		xhci_dbg(xhci, "No hcd found for port %u event\n", port_id);
+		bogus_port_status = true;
+		goto cleanup;
+	}
+
 	if (major_revision == 0) {
 		xhci_warn(xhci, "Event for port %u not in "
 				"Extended Capabilities, ignoring.\n",