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

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Message-ID: <371b3697614e4034aed8e9f340a7dbf1@zhaoxin.com>
Date:   Thu, 23 Jul 2020 08:36:25 +0000
From:   WeitaoWang-oc <WeitaoWang-oc@...oxin.com>
To:     Alex Williamson <alex.williamson@...hat.com>,
        WeitaoWang-oc <WeitaoWang-oc@...oxin.com>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "mathias.nyman@...ux.intel.com" <mathias.nyman@...ux.intel.com>,
        "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        "hslester96@...il.com" <hslester96@...il.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Carsten_Schmid@...tor.com" <Carsten_Schmid@...tor.com>,
        "efremov@...ux.com" <efremov@...ux.com>,
        "Tony W. Wang(XA-RD)" <TonyWWang@...oxin.com>,
        "Cobe Chen(BJ-RD)" <CobeChen@...oxin.com>,
        "Tim Guo(BJ-RD)" <TimGuo@...oxin.com>,
        "wwt8723@....com" <wwt8723@....com>
Subject: 答复: [PATCH] USB:Fix kernel NULL pointer when unbind UHCI form vfio-pci


On Thu,23 July 2020 04:18:00 +0000 Alex wrote:
> On Wed, 22 Jul 2020 19:57:48 +0800
> WeitaoWangoc <WeitaoWang-oc@...oxin.com> 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