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

[Marek Vasut <marex@denx.de>]

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.

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