linux-kernel - Re: [PATCH] mfd: ene-kb3930: Fix potential NULL pointer dereference

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Message-ID: <CALGdzuqnAtyWSfgqpFbw-fVGvYnYHRGbSH2v8BUSJnpYPXR5Sw@mail.gmail.com>
Date: Mon, 10 Feb 2025 17:47:06 -0600
From: Chenyuan Yang <chenyuan0y@...il.com>
To: Lee Jones <lee@...nel.org>
Cc: lkundrak@...sk, linux-kernel@...r.kernel.org, zijie98@...il.com
Subject: Re: [PATCH] mfd: ene-kb3930: Fix potential NULL pointer dereference

On Mon, Feb 10, 2025 at 11:34 AM Lee Jones <lee@...nel.org> wrote:
>
> On Mon, 20 Jan 2025, Chenyuan Yang wrote:
>
> > The off_gpios could be NULL. Add missing check in the kb3930_probe().
> > This is similar to the issue fixed in commit
> > https://patchwork.kernel.org/project/linux-fbdev/patch/20240114143921.550736-1-andriy.shevchenko@linux.intel.com/> >
> > Fixes: ede6b2d1dfc0 ("mfd: ene-kb3930: Add driver for ENE KB3930 Embedded Controller")
> > Signed-off-by: Chenyuan Yang <chenyuan0y@...il.com>
> > ---
> >  drivers/mfd/ene-kb3930.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/mfd/ene-kb3930.c b/drivers/mfd/ene-kb3930.c
> > index fa0ad2f14a39..60824d847bf0 100644
> > --- a/drivers/mfd/ene-kb3930.c
> > +++ b/drivers/mfd/ene-kb3930.c
> > @@ -162,6 +162,8 @@ static int kb3930_probe(struct i2c_client *client)
> >                       devm_gpiod_get_array_optional(dev, "off", GPIOD_IN);
> >               if (IS_ERR(ddata->off_gpios))
> >                       return PTR_ERR(ddata->off_gpios);
> > +             if (!ddata->off_gpios)
> > +                     return -ENOMEM;
>
> I don't see many other call sites checking for NULL - why is this
> different?

It looks like other places using devm_gpiod_get_array_optional do
check for a NULL return value, such as in
drivers/iio/resolver/ad2s1210.c, drivers/mtd/maps/physmap-core.c, and
this patch commit:
https://patchwork.kernel.org/project/linux-fbdev/patch/20240114143921.550736-1-andriy.shevchenko@linux.intel.com/.

> What about IS_ERR_OR_NULL() instead?

Yes, that sounds good. However, I have a question—what error number
should be returned in this case?

> >               if (ddata->off_gpios->ndescs < 2) {
> >                       dev_err(dev, "invalid off-gpios property\n");
> >                       return -EINVAL;
> > --
> > 2.34.1
> >
>
> --
> Lee Jones [李琼斯]

-Chenyuan