Re: [PATCH v2] usbip: vhci_hcd: fix calling usb_hcd_giveback_urb() with irqs enabled

[Andrey Konovalov]

On Wed, Oct 7, 2020 at 12:39 AM Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote:
>
> kcov testing uncovered call to usb_hcd_giveback_urb() without disabling
> interrupts.
>
> Link: https://lore.kernel.org/linux-usb/CAAeHK+wb4k-LGTjK9F5YbJNviF_+yU+wE_=Vpo9Rn7KFN8vG6Q@xxxxxxxxxxxxxx/
>
> usb_hcd_giveback_urb() is called from vhci's urb_enqueue, when it
> determines it doesn't need to xmit the urb and can give it back.
> This path runs in task context.
>
> Disable irqs around usb_hcd_giveback_urb() call.
>
> Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Suggested-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>

Acked-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>

Thank you!

> ---
>
> Changes in v2: Changelog updated with correct information.
>  drivers/usb/usbip/vhci_hcd.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
> index 1b598db5d8b9..66cde5e5f796 100644
> --- a/drivers/usb/usbip/vhci_hcd.c
> +++ b/drivers/usb/usbip/vhci_hcd.c
> @@ -797,8 +797,14 @@ static int vhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flag
>         usb_hcd_unlink_urb_from_ep(hcd, urb);
>  no_need_unlink:
>         spin_unlock_irqrestore(&vhci->lock, flags);
> -       if (!ret)
> +       if (!ret) {
> +               /* usb_hcd_giveback_urb() should be called with
> +                * irqs disabled
> +                */
> +               local_irq_disable();
>                 usb_hcd_giveback_urb(hcd, urb, urb->status);
> +               local_irq_enable();
> +       }
>         return ret;
>  }
>
> --
> 2.25.1
>