Re: [RFT PATCH 2/2] xhci: handle port status events for removed USB3 hcd

[Mathias Nyman]

On 27.09.2018 19:26, Mathias Nyman wrote:

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: <sta...@vger.kernel.org>
Reported-by: Peter Chen <peter.c...@nxp.com>
Signed-off-by: Mathias Nyman <mathias.ny...@linux.intel.com>
---
  drivers/usb/host/xhci-ring.c | 7 +++++++
  1 file changed, 7 insertions(+)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index f0a99aa..3d314b8 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1552,6 +1552,13 @@ static void handle_port_status(struct xhci_hcd *xhci,
                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;

This probably only applies from 4.18 onwards, to test on older kernel try 
something
like this instead:

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 6996235..7925da9 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1606,7 +1606,11 @@ static void handle_port_status(struct xhci_hcd *xhci,
        hcd = xhci_to_hcd(xhci);
        if ((major_revision == 0x03) != (hcd->speed >= HCD_USB3))
                hcd = xhci->shared_hcd;
-
+       if (!hcd) {
+               bogus_port_status = true;
+               goto cleanup;
+       }
        if (major_revision == 0) {
                xhci_warn(xhci, "Event for port %u not in "
                                "Extended Capabilities, ignoring.\n",


Jack, Peter, do these patches solve the remove issues you are seeing?

Thanks
-Mathias