iio: adc: tsc2046: fix memory corruption by preventing array overflow

commit b7a78a8adaa8849c02f174d707aead0f85dca0da upstream.

On one side we have indio_dev->num_channels includes all physical channels +
timestamp channel. On other side we have an array allocated only for
physical channels. So, fix memory corruption by ARRAY_SIZE() instead of
num_channels variable.

Note the first case is a cleanup rather than a fix as the software
timestamp channel bit in active_scanmask is never set by the IIO core.

Fixes: 9374e8f5a38d ("iio: adc: add ADC driver for the TI TSC2046 controller")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20220107081401.2816357-1-o.rempel@pengutronix.de
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/adc/ti-tsc2046.c b/drivers/iio/adc/ti-tsc2046.c
index d84ae6b..e8fc4d0 100644 (file)
--- a/drivers/iio/adc/ti-tsc2046.c
+++ b/drivers/iio/adc/ti-tsc2046.c
@@ -388,7 +388,7 @@ static int tsc2046_adc_update_scan_mode(struct iio_dev *indio_dev,
        mutex_lock(&priv->slock);
 
        size = 0;
-       for_each_set_bit(ch_idx, active_scan_mask, indio_dev->num_channels) {
+       for_each_set_bit(ch_idx, active_scan_mask, ARRAY_SIZE(priv->l)) {
                size += tsc2046_adc_group_set_layout(priv, group, ch_idx);
                tsc2046_adc_group_set_cmd(priv, group, ch_idx);
                group++;
@@ -548,7 +548,7 @@ static int tsc2046_adc_setup_spi_msg(struct tsc2046_adc_priv *priv)
         * enabled.
         */
        size = 0;
-       for (ch_idx = 0; ch_idx < priv->dcfg->num_channels; ch_idx++)
+       for (ch_idx = 0; ch_idx < ARRAY_SIZE(priv->l); ch_idx++)
                size += tsc2046_adc_group_set_layout(priv, ch_idx, ch_idx);
 
        priv->tx = devm_kzalloc(&priv->spi->dev, size, GFP_KERNEL);