[PATCH v2 02/12] iio: adc: ad7124: Fix potential overflow due to non sequential channel numbers

From: Alexandru Ardelean
Date: Tue May 11 2021 - 03:18:47 EST


From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>

Channel numbering must start at 0 and then not have any holes, or
it is possible to overflow the available storage. Note this bug was
introduced as part of a fix to ensure we didn't rely on the ordering
of child nodes. So we need to support arbitrary ordering but they all
need to be there somewhere.

Note I hit this when using qemu to test the rest of this series.
Arguably this isn't the best fix, but it is probably the most minimal
option for backporting etc.

Fixes: d7857e4ee1ba6 ("iio: adc: ad7124: Fix DT channel configuration")
Reviewed-by: Alexandru Ardelean <ardeleanalex@xxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Alexandru Ardelean <aardelean@xxxxxxxxxxx>
---
drivers/iio/adc/ad7124.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 437116a07cf1..a27db78ea13e 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -771,6 +771,13 @@ static int ad7124_of_parse_channel_config(struct iio_dev *indio_dev,
if (ret)
goto err;

+ if (channel >= indio_dev->num_channels) {
+ dev_err(indio_dev->dev.parent,
+ "Channel index >= number of channels\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
ret = of_property_read_u32_array(child, "diff-channels",
ain, 2);
if (ret)
--
2.31.1