linux-kernel - Re: [PATCH] iio: adc: palmas_gpadc: fix NULL dereference on rmmod

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Message-ID: <20230318192253.GB3605556@dalakolonin.se>
Date:   Sat, 18 Mar 2023 20:22:53 +0100
From:   Patrik Dahlström <risca@...akolonin.se>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     lars@...afoo.de, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org, hns@...delico.com
Subject: Re: [PATCH] iio: adc: palmas_gpadc: fix NULL dereference on rmmod

On Sat, Mar 18, 2023 at 04:30:33PM +0000, Jonathan Cameron wrote:
> On Mon, 13 Mar 2023 21:50:29 +0100
> Patrik Dahlström <risca@...akolonin.se> wrote:
> 
> > Calling dev_to_iio_dev() on a platform device pointer is undefined and
> > will make adc NULL.
> > 
> > Signed-off-by: Patrik Dahlström <risca@...akolonin.se>
> 
> Hi Patrik,
> 
> Looks good so applied to the fixes-togreg branch of iio.git.
> 
> Whilst we are here, this would be a trivial driver to take fully device
> managed.  The only slightly messy bit is that it would need
> a devm_add_action_or_reset() + custom callback to handle the
> device_wakeup_enable().
> 
> On the off chance you can test it I'll send a patch in a few mins.
> Note that will depend on this one going up stream first and that
> I haven't done more than build test it.
I got the patch and it looks good, but it will take a few days before I
have the time to test it.

I have some more patches coming for this driver to configure the adc
thresholds from userspace, employing the iio channel event subsystem, but
they need a bit more work. In particular, to ensure backwards compatibility
with the adc_wakeupX_data platform data. However, I don't see this platform
data being used by anyone.
How important is it to retain support for adc_wakeupX_data?
> 
> Thanks,
> 
> Jonathan

Thank you for going the extra mile :)
> 
> 
> > ---
> >  drivers/iio/adc/palmas_gpadc.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/adc/palmas_gpadc.c b/drivers/iio/adc/palmas_gpadc.c
> > index 61e80bf3d05e..6db6f3bc768a 100644
> > --- a/drivers/iio/adc/palmas_gpadc.c
> > +++ b/drivers/iio/adc/palmas_gpadc.c
> > @@ -638,7 +638,7 @@ static int palmas_gpadc_probe(struct platform_device *pdev)
> >  
> >  static int palmas_gpadc_remove(struct platform_device *pdev)
> >  {
> > -	struct iio_dev *indio_dev = dev_to_iio_dev(&pdev->dev);
> > +	struct iio_dev *indio_dev = dev_get_drvdata(&pdev->dev);
> >  	struct palmas_gpadc *adc = iio_priv(indio_dev);
> >  
> >  	if (adc->wakeup1_enable || adc->wakeup2_enable)
>