Re: rtl8xxxu 4.4.5(from f23): I get a panic adding a new device to the driver

[Greg KH <greg@kroah.com>]

On Thu, Mar 17, 2016 at 09:01:25PM +0100, poma wrote:
> On 17.03.2016 19:02, Jes Sorensen wrote:
> > Jes Sorensen <Jes.Sorensen@redhat.com> writes:
> >> Xose Vazquez Perez <xose.vazquez@gmail.com> writes:
> >>> Hi,
> >>>
> >>> If I do:
> >>> # echo "0bda 8176" > /sys/bus/usb/drivers/rtl8xxxu/new_id
> >>
> >> Hi Xose,
> >>
> >> Yes please don't do that. The rtl8xxxu driver relies on the .driver_info
> >> field in struct use_device_id to carry information for the different
> >> types of devices. If you hot add a device like above, the driver will
> >> fail because that field now contains a NULL pointer.
> >>
> >> I should probably add a check for it in the probe function, but it will
> >> simply be there to spit out a warning that it doesn't work to hot add a
> >> device like this.
> >>
> >> If you build it with CONFIG_RTL8XXXU_UNTESTED the 0bda:8176 should be
> >> included in the device list.
> >>
> >> Cheers,
> >> Jes
> > 
> > Hi Xose,
> > 
> > I added the following patch to my tree to avoid this.
> > 
> > Cheers,
> > Jes
> > 
> > commit 9202f4947aac1d60084ee79c9b5294eb42ba59dc
> > Author: Jes Sorensen <Jes.Sorensen@redhat.com>
> > Date:   Thu Mar 17 13:53:48 2016 -0400
> > 
> >     rtl8xxxu: Fix OOPS if user tries to add device via /sys
> >     
> >     This driver relies on driver_info in struct usb_device_id, hence
> >     adding a device via  /sys/bus/usb/drivers/rtl8xxxu/new_id would result
> >     in a NULL pointer dereference.
> >     
> >     Instead print a message and return -ENODEV
> >     
> >     Reported-by: Xose Vazquez Perez <xose.vazquez@gmail.com>
> >     Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
> > 
> > diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
> > index 8d893f4..55fc00e 100644
> > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
> > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.c
> > @@ -9671,6 +9671,15 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
> >  
> >  	udev = usb_get_dev(interface_to_usbdev(interface));
> >  
> > +	if (!id->driver_info) {
> > +		dev_warn(&udev->dev,
> > +			 "rtl8xxxu relies on driver_info in struct usb_device_id.\n");
> > +		dev_warn(&udev->dev,
> > +			 "Adding a device via /sys/bus/usb/drivers/rtl8xxxu/new_id is not supported!\n");

We do have a flag in the USB driver structure to prevent this from
happening, "no_dynamic_id", please just set that and then this should
not happen.

thanks,

gre k-h