[PATCH v2] hwmon:(stts751) buffer overread on wrong chip configuration

[Anton Vasilyev]

If stts751 hw by some reason reports conversion rate bigger then 9:
        ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_RATE);
then dereference stts751_intervals[priv->interval] leads to buffer
overread.

The path adds sanity check for value stored on chip.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@xxxxxxxxx>
---
v2: Fixed Guenter's remark about comparison
---
 drivers/hwmon/stts751.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/hwmon/stts751.c b/drivers/hwmon/stts751.c
index d56251d..3f940fb 100644
--- a/drivers/hwmon/stts751.c
+++ b/drivers/hwmon/stts751.c
@@ -718,6 +718,10 @@ static int stts751_read_chip_config(struct stts751_priv *priv)
 	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_RATE);
 	if (ret < 0)
 		return ret;
+	if (ret >= ARRAY_SIZE(stts751_intervals)) {
+		dev_err(priv->dev, "Unrecognized conversion rate 0x%x\n", ret);
+		return -ENODEV;
+	}
 	priv->interval = ret;
 
 	ret = stts751_read_reg16(priv, &priv->event_max,
-- 
2.7.4