Re: [PATCH v3] iio: core: Print error in case sample bits do not fit storage bits

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Mon, Mar 28, 2022 at 09:53:07PM +0200, Marek Vasut wrote:
> Add runtime check to verify whether storagebits are at least as big
> as shifted realbits. This should help spot broken drivers which may
> set realbits + shift above storagebits.

Let's go with it.
Reviewed-by: Andy Shevchenko <andy@kernel.org>

> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Andy Shevchenko <andy@kernel.org>
> Cc: Daniel Baluta <daniel.baluta@nxp.com>
> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
> V2: Use dev_err() instead as WARN_ON() may panic() the kernel on existing machines
> V3: Abort probe and return -EINVAL in case this condition is triggered
> ---
>  drivers/iio/industrialio-buffer.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index b078eb2f3c9de..75a1c57b49102 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -1629,6 +1629,19 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
>  			if (channels[i].scan_index < 0)
>  				continue;
>  
> +			/* Verify that sample bits fit into storage */
> +			if (channels[i].scan_type.storagebits <
> +			    channels[i].scan_type.realbits +
> +			    channels[i].scan_type.shift) {
> +				dev_err(&indio_dev->dev,
> +					"Channel %d storagebits (%d) < shifted realbits (%d + %d)\n",
> +					i, channels[i].scan_type.storagebits,
> +					channels[i].scan_type.realbits,
> +					channels[i].scan_type.shift);
> +				ret = -EINVAL;
> +				goto error_cleanup_dynamic;
> +			}
> +
>  			ret = iio_buffer_add_channel_sysfs(indio_dev, buffer,
>  							 &channels[i]);
>  			if (ret < 0)
> -- 
> 2.35.1
> 

-- 
With Best Regards,
Andy Shevchenko