Re: [PATCH 6/9] iio: adc: ti-adc128s052: validate SPI match data

[Jonathan Cameron <jic23@kernel.org>]

On Sat, 26 Sep 2026 02:18:23 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> On Sat, 26 Sep 2026 02:15:06 +0100
> Jonathan Cameron <jic23@kernel.org> wrote:
> 
> > On Fri, 25 Sep 2026 20:57:44 +0800
> > Jiale Yao <yaojiale02@163.com> wrote:
> >   
> > > SPI driver_override allows a device to bind to this driver without
> > > matching either the firmware tables or SPI device ID table. In that
> > > case, spi_get_device_match_data() returns NULL.
> > > 
> > > adc128_probe() also obtains the IIO device name by dereferencing the
> > > result of spi_get_device_id(), which is NULL on the same override path.
> > > The probe can therefore crash before it reaches the match data access.
> > > 
> > > Commit 572a00852635 ("iio: dac: ad5686: missing NULL check on match
> > > data") fixed the same driver_override issue in another SPI driver.
> > > Reject devices without match data and use the always available SPI
> > > modalias for the IIO device name.    
> > 
> > Why this change?  The name is clearly encoded in a place that makes
> > it readily available and verifiably the right thing in a way that
> > spi->modalias does not.
> > There isn't any reason the IIO name would always match that even it
> > happens to do so here.  
> 
> Actually - ignore that, I misread this and assumed the code
> was different from what was actually there.
> 
> Drivers shouldn't be using spi_get_device_id(spi)->name but
> I'm not sure modalias is any better.
> 
> I'm out of time for now, so will revisit this in a day or so.
> 

I did a bit of LLM assisted digging and it does seem that some
of the previous issues around these names and ACPI PRP0001 have
been resolved these days so as far as I can tell this ends
up the with the correct answer.

> > 
> >   
> > > 
> > > Fixes: d5f0da0c6972 ("iio: adc: ti-adc128s052: Switch to use spi_get_device_match_data()")
> > > Cc: stable@vger.kernel.org
> > > Signed-off-by: Jiale Yao <yaojiale02@163.com>
> > > ---
> > >  drivers/iio/adc/ti-adc128s052.c | 8 +++++---
> > >  1 file changed, 5 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
> > > index 1899813c1aee..f9a995ff403e 100644
> > > --- a/drivers/iio/adc/ti-adc128s052.c
> > > +++ b/drivers/iio/adc/ti-adc128s052.c
> > > @@ -195,12 +195,14 @@ static int adc128_probe(struct spi_device *spi)
> > >  	adc = iio_priv(indio_dev);
> > >  	adc->spi = spi;
> > >  
> > > -	indio_dev->name = spi_get_device_id(spi)->name;
> > > +	config = spi_get_device_match_data(spi);
> > > +	if (!config)
> > > +		return -ENODATA;
> > > +
> > > +	indio_dev->name = spi->modalias;
> > >  	indio_dev->modes = INDIO_DIRECT_MODE;
> > >  	indio_dev->info = &adc128_info;
> > >  
> > > -	config = spi_get_device_match_data(spi);
> > > -
> > >  	indio_dev->channels = config->channels;
> > >  	indio_dev->num_channels = config->num_channels;
> > >      
> > 
> >   
> 
>