[PATCH 4.19 009/110] xhci: handle port status events for removed USB3 hcd

[Greg Kroah-Hartman]

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

------------------

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/host/xhci-ring.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1552,6 +1552,13 @@ static void handle_port_status(struct xh
 		goto cleanup;
 	}
 
+	/* We might get interrupts after shared_hcd is removed */
+	if (port->rhub == &xhci->usb3_rhub && xhci->shared_hcd == NULL) {
+		xhci_dbg(xhci, "ignore port event for removed USB3 hcd\n");
+		bogus_port_status = true;
+		goto cleanup;
+	}
+
 	hcd = port->rhub->hcd;
 	bus_state = &xhci->bus_state[hcd_index(hcd)];
 	hcd_portnum = port->hcd_portnum;