çå: [PATCH] USB:Fix kernel NULL pointer when unbind UHCI form vfio-pci

[WeitaoWang-oc]

On Thu,23 July 2020 04:18:00 +0000 Alex wrote:
> On Wed, 22 Jul 2020 19:57:48 +0800
> WeitaoWangoc <WeitaoWang-oc@xxxxxxxxxxx> wrote:
> 
> >  drivers/usb/core/hcd-pci.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c
> > index 1547aa6..484f2a0 100644
> > --- a/drivers/usb/core/hcd-pci.c
> > +++ b/drivers/usb/core/hcd-pci.c
> > @@ -34,6 +34,7 @@ static DECLARE_RWSEM(companions_rwsem);
> >  #define CL_OHCI                PCI_CLASS_SERIAL_USB_OHCI
> >  #define CL_EHCI                PCI_CLASS_SERIAL_USB_EHCI
> >
> > +#define PCI_DEV_DRV_FLAG       2
> >  static inline int is_ohci_or_uhci(struct pci_dev *pdev)  {
> >         return pdev->class == CL_OHCI || pdev->class == CL_UHCI; @@
> > -68,6 +69,8 @@ static void for_each_companion(struct pci_dev *pdev, struct
> usb_hcd *hcd,
> >                 if (companion->class != CL_UHCI && companion->class !=
> CL_OHCI &&
> >                                 companion->class != CL_EHCI)
> >                         continue;
> > +               if (!(companion->priv_flags & PCI_DEV_DRV_FLAG))
> 
> But pci_dev.priv_flags is private data for the driver that currently
> owns the device, which could be vfio-pci.  This is really no different
> than assuming the structure at device.driver_data.  If vfio-pci were to
> make legitimate use of pci_dev.priv_flags, this could simply blow up
> again.  Should there instead be some sort of registration interface
> where hcd complaint drivers register their devices and only those
> registered devices can have their driver private data arbitrarily poked
> by another driver?  Thanks,

Thanks for your explanation. Set pci_dev.priv_flags is really not a 
reasonable approach. Are there any more detailed suggestions 
to patch this issue?

Thanks
Weitaowang