[PATCH 3/7] iio: dac: mcp4821: reject devices without match data

[Jiale Yao <yaojiale02@163.com>]

A device bound through driver_override need not match an entry in the
driver tables. In that case spi_get_device_match_data() returns NULL,
but mcp4821_probe() dereferences the result while configuring the IIO
device.

Reject devices without match data before using the chip information.

Fixes: cdf3ecb0d8d0 ("iio: dac: driver for MCP4821")
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 drivers/iio/dac/mcp4821.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/dac/mcp4821.c b/drivers/iio/dac/mcp4821.c
index 8d8c00cd60e9..59defb1b5e62 100644
--- a/drivers/iio/dac/mcp4821.c
+++ b/drivers/iio/dac/mcp4821.c
@@ -255,9 +255,13 @@ static const struct iio_info mcp4821_info = {
 
 static int mcp4821_probe(struct spi_device *spi)
 {
+	const struct mcp4821_chip_info *info;
 	struct iio_dev *indio_dev;
 	struct mcp4821_state *state;
-	const struct mcp4821_chip_info *info;
+
+	info = spi_get_device_match_data(spi);
+	if (!info)
+		return -ENODATA;
 
 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
 	if (indio_dev == NULL)
@@ -268,7 +272,6 @@ static int mcp4821_probe(struct spi_device *spi)
 
 	/* default gain is 2x */
 	state->gain = 2;
-	info = spi_get_device_match_data(spi);
 	indio_dev->name = info->name;
 	indio_dev->info = &mcp4821_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
-- 
2.34.1