On Wed, 2023-03-01 at 10:33 -0500, Alan Stern wrote:
> On Wed, Mar 01, 2023 at 01:23:09PM +0100, Bastien Nocera wrote:
> > This adds the API that allows device specific drivers to tell user-
> > space
> > about whether the wireless device is connected to its receiver
> > dongle.
> >
> > See "USB: core: Add wireless_status sysfs attribute" for a detailed
> > explanation of what this attribute should be used for.
> >
> > Signed-off-by: Bastien Nocera <hadess@xxxxxxxxxx>
> > ---
> > Fixed locking/use-after-free in v2, thanks to Alan Stern
> >
> > drivers/usb/core/message.c | 40
> > ++++++++++++++++++++++++++++++++++++++
> > include/linux/usb.h | 5 +++++
> > 2 files changed, 45 insertions(+)
> >
> > diff --git a/drivers/usb/core/message.c
> > b/drivers/usb/core/message.c
> > index 127fac1af676..3867d9a85145 100644
> > --- a/drivers/usb/core/message.c
> > +++ b/drivers/usb/core/message.c
> > @@ -1908,6 +1908,45 @@ static void __usb_queue_reset_device(struct
> > work_struct *ws)
> > usb_put_intf(iface); /* Undo _get_ in
> > usb_queue_reset_device() */
> > }
> >
> > +/*
> > + * Internal function to set the wireless_status sysfs attribute
> > + * See usb_set_wireless_status() for more details
> > + */
> > +static void __usb_wireless_status_intf(struct work_struct *ws)
> > +{
> > + struct usb_interface *iface =
> > + container_of(ws, struct usb_interface,
> > wireless_status_work);
> > +
> > + device_lock(iface->dev.parent);
> > + if (iface->sysfs_files_created)
> > + usb_update_wireless_status_attr(iface);
> > + usb_put_intf(iface); /* Undo _get_ in
> > usb_set_wireless_status() */
> > + device_unlock(iface->dev.parent);
>
> Whoops! Calling usb_put_intf() means the iface pointer is no longer
> valid. The device_unlock() call should come before it, not after.
Fixed this in v3.
> PS: You might also want to edit the sysfs documentation in the
> preceding
> patch, to make sure the text doesn't extend beyond the 80-column
> limit.
> I know people don't pay too much attention to that restriction in
> code
> any more, but in documentation it helps to keep the lines fairly
> short.
> People have trouble reading text when the lines get too long.
That's an easy fix, so done in v3 as well.
