Re: [PATCH] iio: adc: ad7768-1: Fix ERR_PTR dereference in ad7768_fill_scale_tbl

["Nuno Sá" <noname.nuno@gmail.com>]

On Thu, 2026-02-12 at 21:12 -0600, Ethan Tidmore wrote:
> The function iio_get_current_scan_type() can return ERR_PTR, the return
> value scan_type is not checked for this and immediately dereferenced
> which can cause a kernel panic.
> 
> Add check for IS_ERR() and return early to avoid crash.
> 
> Fixes: ff085189cb17 ("iio: adc: ad7768-1: add support for ADAQ776x-1 ADC Family")
> Signed-off-by: Ethan Tidmore <ethantidmore06@gmail.com>
> ---
>  drivers/iio/adc/ad7768-1.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index fcd8aea7152e..f45a09e39367 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -541,6 +541,11 @@ static void ad7768_fill_scale_tbl(struct iio_dev *dev)
>  	u64 tmp2;
>  
>  	scan_type = iio_get_current_scan_type(dev, &dev->channels[0]);
> +	if (IS_ERR(scan_type)) {
> +		dev_err(&st->spi->dev, "Failed to get scan type.\n");
> +		return;
> +	}
> +

With the above, it could make sense to change the function to propagate the error back...

- Nuno Sá

>  	if (scan_type->sign == 's')
>  		val2 = scan_type->realbits - 1;
>  	else