On Fri, Feb 26, 2021 at 01:54:12PM -0800, Saravana Kannan wrote:
> On Fri, Feb 26, 2021 at 6:55 AM Johan Hovold <jo...@kernel.org> wrote:
> >
> > Fix a NULL-pointer deference when deregistering the gpio character
> > device that was introduced by the recent stub-driver hack. When the new
> > "driver" is unbound as part of deregistration, driver core clears the
> > driver-data pointer which is used to retrieve the struct gpio_device in
> > its release callback.
> >
> > Fix this by using container_of() in the release callback as should have
> > been done all along.
> >
> > Fixes: 4731210c09f5 ("gpiolib: Bind gpio_device to a driver to enable
> > fw_devlink=on by default")
> > Cc: Saravana Kannan <sarava...@google.com>
> > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> > Reported-by: syzbot+d27b4c8adbbff70fb...@syzkaller.appspotmail.com
> > Signed-off-by: Johan Hovold <jo...@kernel.org>
> > ---
> > drivers/gpio/gpiolib.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > index adf55db080d8..e1016bc8cf14 100644
> > --- a/drivers/gpio/gpiolib.c
> > +++ b/drivers/gpio/gpiolib.c
> > @@ -474,7 +474,7 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
> >
> > static void gpiodevice_release(struct device *dev)
> > {
> > - struct gpio_device *gdev = dev_get_drvdata(dev);
> > + struct gpio_device *gdev = container_of(dev, struct gpio_device,
> > dev);
>
> Can you also delete the dev_set_drvdata() in
> gpiochip_add_data_with_key() if the drvdata is not used
> elsewhere anymore? I skimmed the code and it doesn't look like it, but
> I could be wrong.
Yeah, I considered it but didn't want to risk introducing any new
regressions just to clean up a redundant store.
But looking at it again today, I agree that it looks like it isn't used
anywhere else. I'll send a v2. Thanks.
Johan
