Re: [PATCH] leds: fix a potential NULL pointer dereference

[Jacek Anaszewski]

Hi Linus,

Yesterday I submitted pull request [0] containing this patch, but
the patch turns out to be pointless. Since I see my pull request merged
on top of mainline trunk I suspect it will not be a problem to
drop the patch or even whole pull request. In the latter case I'll
re-submit it for -rc4.

Sorry for the confusion.

Best regards,
Jacek Anaszewski

On 3/31/19 11:06 AM, Geert Uytterhoeven wrote:
> Hi Jacek,
>
> On Sun, Mar 10, 2019 at 9:40 PM Jacek Anaszewski
> <jacek.anaszewski@xxxxxxxxx> wrote:
> > On 3/9/19 7:04 AM, Kangjie Lu wrote:
> > > In case of_match_device cannot find a match, the fixes returns
> > > -EINVAL to avoid NULL pointer dereference.
> > >
> > > Signed-off-by: Kangjie Lu <kjlu@xxxxxxx>
> > > ---
> > >    drivers/leds/leds-pca9532.c | 8 ++++++--
> > >    1 file changed, 6 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/leds/leds-pca9532.c b/drivers/leds/leds-pca9532.c
> > > index 7fea18b0c15d..4b0335591728 100644
> > > --- a/drivers/leds/leds-pca9532.c
> > > +++ b/drivers/leds/leds-pca9532.c
> > > @@ -513,6 +513,7 @@ static int pca9532_probe(struct i2c_client *client,
> > >        const struct i2c_device_id *id)
> > >    {
> > >        int devid;
> > > +     const struct of_device_id *of_id;
> > >        struct pca9532_data *data = i2c_get_clientdata(client);
> > >        struct pca9532_platform_data *pca9532_pdata =
> > >                        dev_get_platdata(&client->dev);
> > > @@ -528,8 +529,11 @@ static int pca9532_probe(struct i2c_client *client,
> > >                        dev_err(&client->dev, "no platform data\n");
> > >                        return -EINVAL;
> > >                }
> > > -             devid = (int)(uintptr_t)of_match_device(
> > > -                     of_pca9532_leds_match, &client->dev)->data;
> > > +             of_id = of_match_device(of_pca9532_leds_match,
> > > +                             &client->dev);
> > > +             if (unlikely(!of_id))
>
> Use of unlikey() is frowned upon.
> Moreover, this cannot happen, as pca9532_of_populate_pdata() already
> contains a similar check.
>
> Kangjie: please stop submitting patches for missing checks, without
> investigating if the failures can actually happen. Thanks!
>
> > > +                     return -EINVAL;
> > > +             devid = (int)of_id->data;
> > >        } else {
> > >                devid = id->driver_data;
> > >        }
> >
> >
> > Applied to the for-5.2 branch of linux-leds.git.
>
> And also as a fix for v5.1...
>
> Gr{oetje,eeting}s,
>
>                          Geert

[0] https://lkml.org/lkml/2019/3/30/222