[PATCH 2/9] iio: adc: ad7606: reject devices without match data

[Jiale Yao <yaojiale02@163.com>]

SPI driver_override allows a device to bind to this driver without
matching either the OF or SPI device ID table. In that case,
spi_get_device_match_data() returns NULL.

ad7606_spi_probe() dereferences the returned bus information to pass
the chip information and bus operations to the core, causing a NULL
pointer dereference.

Commit 572a00852635 ("iio: dac: ad5686: missing NULL check on match
data") fixed the same driver_override issue in another SPI driver.
Reject devices without match data before entering the core.

Fixes: bc69e9fffde4 ("iio: adc: ad7606: Add compatibility to fw_nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 drivers/iio/adc/ad7606_spi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7606_spi.c b/drivers/iio/adc/ad7606_spi.c
index 1ebdfb8580ab..8c479fa50a23 100644
--- a/drivers/iio/adc/ad7606_spi.c
+++ b/drivers/iio/adc/ad7606_spi.c
@@ -456,7 +456,11 @@ static const struct ad7606_bus_info ad7616_bus_info = {
 
 static int ad7606_spi_probe(struct spi_device *spi)
 {
-	const struct ad7606_bus_info *bus_info = spi_get_device_match_data(spi);
+	const struct ad7606_bus_info *bus_info;
+
+	bus_info = spi_get_device_match_data(spi);
+	if (!bus_info)
+		return -ENODATA;
 
 	return ad7606_probe(&spi->dev, spi->irq, NULL,
 			    bus_info->chip_info, bus_info->bops);
-- 
2.34.1