iio: adc: ad4851: fix ad4858 chan pointer handling

[PATCH] iio: adc: ad4851: fix ad4858 chan pointer handling

Posted by Antoniu Miclaus 7 months, 2 weeks ago

The pointer returned from ad4851_parse_channels_common() is incremented
internally as each channel is populated. In ad4858_parse_channels(),
the same pointer was further incremented while setting ext_scan_type
fields for each channel. This resulted in indio_dev->channels being set
to a pointer past the end of the allocated array, potentially causing
memory corruption or undefined behavior.

Fix this by iterating over the channels using an explicit index instead
of incrementing the pointer. This preserves the original base pointer
and ensures all channel metadata is set correctly.

Fixes: 6250803fe2ec ("iio: adc: ad4851: add ad485x driver")
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
 drivers/iio/adc/ad4851.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/adc/ad4851.c b/drivers/iio/adc/ad4851.c
index 98ebc853db79..f1d2e2896f2a 100644
--- a/drivers/iio/adc/ad4851.c
+++ b/drivers/iio/adc/ad4851.c
@@ -1034,7 +1034,7 @@ static int ad4858_parse_channels(struct iio_dev *indio_dev)
 	struct device *dev = &st->spi->dev;
 	struct iio_chan_spec *ad4851_channels;
 	const struct iio_chan_spec ad4851_chan = AD4858_IIO_CHANNEL;
-	int ret;
+	int ret, i = 0;
 
 	ret = ad4851_parse_channels_common(indio_dev, &ad4851_channels,
 					   ad4851_chan);
@@ -1042,15 +1042,15 @@ static int ad4858_parse_channels(struct iio_dev *indio_dev)
 		return ret;
 
 	device_for_each_child_node_scoped(dev, child) {
-		ad4851_channels->has_ext_scan_type = 1;
+		ad4851_channels[i].has_ext_scan_type = 1;
 		if (fwnode_property_read_bool(child, "bipolar")) {
-			ad4851_channels->ext_scan_type = ad4851_scan_type_20_b;
-			ad4851_channels->num_ext_scan_type = ARRAY_SIZE(ad4851_scan_type_20_b);
+			ad4851_channels[i].ext_scan_type = ad4851_scan_type_20_b;
+			ad4851_channels[i].num_ext_scan_type = ARRAY_SIZE(ad4851_scan_type_20_b);
 		} else {
-			ad4851_channels->ext_scan_type = ad4851_scan_type_20_u;
-			ad4851_channels->num_ext_scan_type = ARRAY_SIZE(ad4851_scan_type_20_u);
+			ad4851_channels[i].ext_scan_type = ad4851_scan_type_20_u;
+			ad4851_channels[i].num_ext_scan_type = ARRAY_SIZE(ad4851_scan_type_20_u);
 		}
-		ad4851_channels++;
+		i++;
 	}
 
 	indio_dev->channels = ad4851_channels;
-- 
2.49.0

Re: [PATCH] iio: adc: ad4851: fix ad4858 chan pointer handling

Posted by Nuno Sá 7 months, 2 weeks ago

On Fri, 2025-05-09 at 13:16 +0300, Antoniu Miclaus wrote:
> The pointer returned from ad4851_parse_channels_common() is incremented
> internally as each channel is populated. In ad4858_parse_channels(),
> the same pointer was further incremented while setting ext_scan_type
> fields for each channel. This resulted in indio_dev->channels being set
> to a pointer past the end of the allocated array, potentially causing
> memory corruption or undefined behavior.
> 
> Fix this by iterating over the channels using an explicit index instead
> of incrementing the pointer. This preserves the original base pointer
> and ensures all channel metadata is set correctly.
> 
> Fixes: 6250803fe2ec ("iio: adc: ad4851: add ad485x driver")
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---

LGTM

Reviewed-by: Nuno Sá <nuno.sa@analog.com>

>  drivers/iio/adc/ad4851.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad4851.c b/drivers/iio/adc/ad4851.c
> index 98ebc853db79..f1d2e2896f2a 100644
> --- a/drivers/iio/adc/ad4851.c
> +++ b/drivers/iio/adc/ad4851.c
> @@ -1034,7 +1034,7 @@ static int ad4858_parse_channels(struct iio_dev
> *indio_dev)
>  	struct device *dev = &st->spi->dev;
>  	struct iio_chan_spec *ad4851_channels;
>  	const struct iio_chan_spec ad4851_chan = AD4858_IIO_CHANNEL;
> -	int ret;
> +	int ret, i = 0;
>  
>  	ret = ad4851_parse_channels_common(indio_dev, &ad4851_channels,
>  					   ad4851_chan);
> @@ -1042,15 +1042,15 @@ static int ad4858_parse_channels(struct iio_dev
> *indio_dev)
>  		return ret;
>  
>  	device_for_each_child_node_scoped(dev, child) {
> -		ad4851_channels->has_ext_scan_type = 1;
> +		ad4851_channels[i].has_ext_scan_type = 1;
>  		if (fwnode_property_read_bool(child, "bipolar")) {
> -			ad4851_channels->ext_scan_type =
> ad4851_scan_type_20_b;
> -			ad4851_channels->num_ext_scan_type =
> ARRAY_SIZE(ad4851_scan_type_20_b);
> +			ad4851_channels[i].ext_scan_type =
> ad4851_scan_type_20_b;
> +			ad4851_channels[i].num_ext_scan_type =
> ARRAY_SIZE(ad4851_scan_type_20_b);
>  		} else {
> -			ad4851_channels->ext_scan_type =
> ad4851_scan_type_20_u;
> -			ad4851_channels->num_ext_scan_type =
> ARRAY_SIZE(ad4851_scan_type_20_u);
> +			ad4851_channels[i].ext_scan_type =
> ad4851_scan_type_20_u;
> +			ad4851_channels[i].num_ext_scan_type =
> ARRAY_SIZE(ad4851_scan_type_20_u);
>  		}
> -		ad4851_channels++;
> +		i++;
>  	}
>  
>  	indio_dev->channels = ad4851_channels;

Re: [PATCH] iio: adc: ad4851: fix ad4858 chan pointer handling

Posted by Jonathan Cameron 7 months, 1 week ago

On Fri, 09 May 2025 13:47:41 +0100
Nuno Sá <noname.nuno@gmail.com> wrote:

> On Fri, 2025-05-09 at 13:16 +0300, Antoniu Miclaus wrote:
> > The pointer returned from ad4851_parse_channels_common() is incremented
> > internally as each channel is populated. In ad4858_parse_channels(),
> > the same pointer was further incremented while setting ext_scan_type
> > fields for each channel. This resulted in indio_dev->channels being set
> > to a pointer past the end of the allocated array, potentially causing
> > memory corruption or undefined behavior.
> > 
> > Fix this by iterating over the channels using an explicit index instead
> > of incrementing the pointer. This preserves the original base pointer
> > and ensures all channel metadata is set correctly.
> > 
> > Fixes: 6250803fe2ec ("iio: adc: ad4851: add ad485x driver")
> > Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> > ---  
> 
> LGTM
Applied to the fixes-togreg branch of iio.git.

Thanks

Jonathan

> 
> Reviewed-by: Nuno Sá <nuno.sa@analog.com>
> 
> >  drivers/iio/adc/ad4851.c | 14 +++++++-------
> >  1 file changed, 7 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/ad4851.c b/drivers/iio/adc/ad4851.c
> > index 98ebc853db79..f1d2e2896f2a 100644
> > --- a/drivers/iio/adc/ad4851.c
> > +++ b/drivers/iio/adc/ad4851.c
> > @@ -1034,7 +1034,7 @@ static int ad4858_parse_channels(struct iio_dev
> > *indio_dev)
> >  	struct device *dev = &st->spi->dev;
> >  	struct iio_chan_spec *ad4851_channels;
> >  	const struct iio_chan_spec ad4851_chan = AD4858_IIO_CHANNEL;
> > -	int ret;
> > +	int ret, i = 0;
> >  
> >  	ret = ad4851_parse_channels_common(indio_dev, &ad4851_channels,
> >  					   ad4851_chan);
> > @@ -1042,15 +1042,15 @@ static int ad4858_parse_channels(struct iio_dev
> > *indio_dev)
> >  		return ret;
> >  
> >  	device_for_each_child_node_scoped(dev, child) {
> > -		ad4851_channels->has_ext_scan_type = 1;
> > +		ad4851_channels[i].has_ext_scan_type = 1;
> >  		if (fwnode_property_read_bool(child, "bipolar")) {
> > -			ad4851_channels->ext_scan_type =
> > ad4851_scan_type_20_b;
> > -			ad4851_channels->num_ext_scan_type =
> > ARRAY_SIZE(ad4851_scan_type_20_b);
> > +			ad4851_channels[i].ext_scan_type =
> > ad4851_scan_type_20_b;
> > +			ad4851_channels[i].num_ext_scan_type =
> > ARRAY_SIZE(ad4851_scan_type_20_b);
> >  		} else {
> > -			ad4851_channels->ext_scan_type =
> > ad4851_scan_type_20_u;
> > -			ad4851_channels->num_ext_scan_type =
> > ARRAY_SIZE(ad4851_scan_type_20_u);
> > +			ad4851_channels[i].ext_scan_type =
> > ad4851_scan_type_20_u;
> > +			ad4851_channels[i].num_ext_scan_type =
> > ARRAY_SIZE(ad4851_scan_type_20_u);
> >  		}
> > -		ad4851_channels++;
> > +		i++;
> >  	}
> >  
> >  	indio_dev->channels = ad4851_channels;  
>