[PATCH] 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 read from chip.

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

Signed-off-by: Anton Vasilyev <vasil...@ispras.ru>
---
 drivers/hwmon/stts751.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/hwmon/stts751.c b/drivers/hwmon/stts751.c
index d56251d..f6eddbd 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