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

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 30 Mar 2022 17:52:13 +0300
Andy Shevchenko <andriy.shevchenko@intel.com> wrote:

> 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>
Agreed.  Applied with a slight change to the title to make it clear
we don't just print the error, we also fail the iio_device_register() call

Applied to the togreg branch of iio.git and pushed out as testing both to let
0-day poke at it and because I will rebase on rc1 once available.

Thanks,

Jonathan

> 
> > 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
> >   
>