iio: adc: tsc2046: add sanity check to avoid to big allocations

To avoid problematic devicetree configurations. Set allocation limit
with error message and suggestion on what can be done to solve this
issue.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20220117082852.3370869-2-o.rempel@pengutronix.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ti-tsc2046.c b/drivers/iio/adc/ti-tsc2046.c
index eb219ff3d61048bbe0262583613823ec8d216c69..2b87f39f377abb05000a3aefb081c08910f3dc75 100644 (file)
--- a/drivers/iio/adc/ti-tsc2046.c
+++ b/drivers/iio/adc/ti-tsc2046.c
@@ -679,6 +679,12 @@ static int tsc2046_adc_setup_spi_msg(struct tsc2046_adc_priv *priv)
        for (ch_idx = 0; ch_idx < priv->dcfg->num_channels; ch_idx++)
                size += tsc2046_adc_group_set_layout(priv, ch_idx, ch_idx);
 
+       if (size > PAGE_SIZE) {
+               dev_err(&priv->spi->dev,
+                       "Calculated scan buffer is too big. Try to reduce spi-max-frequency, settling-time-us or oversampling-ratio\n");
+               return -ENOSPC;
+       }
+
        priv->tx = devm_kzalloc(&priv->spi->dev, size, GFP_KERNEL);
        if (!priv->tx)
                return -ENOMEM;