Re: [PATCH] pwm: sun4i: add NULL check on of_match_device() return value

[Gustavo A. R. Silva]

Hi all,

Quoting Thierry Reding <thierry.reding@xxxxxxxxx>:

> On Fri, Jul 07, 2017 at 03:16:23PM +0800, Chen-Yu Tsai wrote:
> > On Fri, Jul 7, 2017 at 2:39 PM, Gustavo A. R. Silva
> > <garsilva@xxxxxxxxxxxxxx> wrote:
> > > Check return value from call to of_match_device()
> > > in order to prevent a NULL pointer dereference.
> > >
> > > In case of NULL print error message and return -ENODEV
> > >
> > > Signed-off-by: Gustavo A. R. Silva <garsilva@xxxxxxxxxxxxxx>
> > > ---
> > >  drivers/pwm/pwm-sun4i.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > >
> > > diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> > > index 1284ffa..295ca19 100644
> > > --- a/drivers/pwm/pwm-sun4i.c
> > > +++ b/drivers/pwm/pwm-sun4i.c
> > > @@ -321,6 +321,10 @@ static int sun4i_pwm_probe(struct  
> > platform_device *pdev)
> > >         const struct of_device_id *match;
> > >
> > >         match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
> >
> > AFAIK this simply can not and should not fail with a device tree
> > only driver with properly populated of_device_id tables.
>
> Technically this could happen if someone manually created the platform
> device. In that case the core will try to match by name if there is no
> device node to use for a match against the list of of_device_ids.
>
> In my opinion it's best to let things crash in this situation to make
> it really obvious that people have done something wrong.

I get it.

Thanks for clarifying.
--
Gustavo A. R. Silva