On Thu, Feb 27, 2025 at 07:45:29PM +0000, Marc Zyngier wrote:
> When adding support for USB3-over-USB4 tunnelling detection, a check
> for an Intel-specific capability was added. This capability, which
> goes by ID 206, is used without any check that we are actually
> dealing with an Intel host.
>
> As it turns out, the Cadence XHCI controller *also* exposes an
> extended capability numbered 206 (for unknown purposes), but of
> course doesn't have the Intel-specific registers that the tunnelling
> code is trying to access. Fun follows.
>
> The core of the problems is that the tunnelling code blindly uses
> vendor-specific capabilities without any check (the Intel-provided
> documentation I have at hand indicates that 192-255 are indeed
> vendor-specific).
>
> Restrict the detection code to Intel HW for real, preventing any
> further explosion on my (non-Intel) HW.
>
> Cc: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 948ce83fbb7df ("xhci: Add USB4 tunnel detection for USB3 devices on Intel hosts")
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
> drivers/usb/host/xhci-hub.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> index 9693464c05204..69c278b64084b 100644
> --- a/drivers/usb/host/xhci-hub.c
> +++ b/drivers/usb/host/xhci-hub.c
> @@ -12,6 +12,7 @@
> #include <linux/slab.h>
> #include <linux/unaligned.h>
> #include <linux/bitfield.h>
> +#include <linux/pci.h>
>
> #include "xhci.h"
> #include "xhci-trace.h"
> @@ -770,9 +771,16 @@ static int xhci_exit_test_mode(struct xhci_hcd *xhci)
> enum usb_link_tunnel_mode xhci_port_is_tunneled(struct xhci_hcd *xhci,
> struct xhci_port *port)
> {
> + struct usb_hcd *hcd;
> void __iomem *base;
> u32 offset;
>
> + /* Don't try and probe this capability for non-Intel hosts */
> + hcd = xhci_to_hcd(xhci);
> + if (!dev_is_pci(hcd->self.controller) ||
> + to_pci_dev(hcd->self.controller)->vendor != PCI_VENDOR_ID_INTEL)
> + return USB_LINK_UNKNOWN;
Ugh, nice catch.
Mathias, want me to just take this directly for now and not wait for you
to resend it?
thanks,
greg k-h
