Re: [PATCH v4 3/8] iio: core: NULLify private pointer when there is no private data

[David Lechner <dlechner@xxxxxxxxxxxx>]

On Wed, Feb 28, 2024 at 2:50 PM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>
> In iio_device_alloc() when size of the private data is 0,
> the private pointer is calculated to behind the valid data.
> NULLify it for good.
>
> Fixes: 6d4ebd565d15 ("iio: core: wrap IIO device into an iio_dev_opaque object")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
>  drivers/iio/industrialio-core.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 4302093b92c7..bd305fa87093 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -1654,8 +1654,12 @@ struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv)
>                 return NULL;
>
>         indio_dev = &iio_dev_opaque->indio_dev;
> -       indio_dev->priv = (char *)iio_dev_opaque +
> -               ALIGN(sizeof(struct iio_dev_opaque), IIO_DMA_MINALIGN);
> +
> +       if (sizeof_priv)
> +               indio_dev->priv = (char *)iio_dev_opaque +
> +                       ALIGN(sizeof(struct iio_dev_opaque), IIO_DMA_MINALIGN);
> +       else
> +               indio_dev->priv = NULL;

Do we actually need the else branch here since we use kzalloc() and
therefore indio_dev->priv should already be NULL?

>
>         indio_dev->dev.parent = parent;
>         indio_dev->dev.type = &iio_device_type;
> --
> 2.43.0.rc1.1.gbec44491f096
>
>