The "resp.sensor_name" comes from cros_ec_cmd() and it hasn't necessarily
been NUL terminated.  We had not intended to read past "sensor_name_size"
bytes, however, there is a width vs precision bug in the format string.
The format needs to be precision '%.*s' instead of width '%*s'.
Precision prevents an out of bounds read, but width is a no-op.

Fixes: bc3e45258096 ("hwmon: add ChromeOS EC driver")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 drivers/hwmon/cros_ec_hwmon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
index 41f268fa8260..b3ba7247e06b 100644
--- a/drivers/hwmon/cros_ec_hwmon.c
+++ b/drivers/hwmon/cros_ec_hwmon.c
@@ -212,7 +212,7 @@ static void cros_ec_hwmon_probe_temp_sensors(struct device *dev, struct cros_ec_
 			continue;
 
 		sensor_name_size = strnlen(resp.sensor_name, sizeof(resp.sensor_name));
-		priv->temp_sensor_names[i] = devm_kasprintf(dev, GFP_KERNEL, "%*s",
+		priv->temp_sensor_names[i] = devm_kasprintf(dev, GFP_KERNEL, "%.*s",
 							    (int)sensor_name_size,
 							    resp.sensor_name);
 	}
-- 
2.43.0

Thanks!

On 2024-06-06 16:12:11+0000, Dan Carpenter wrote:
> The "resp.sensor_name" comes from cros_ec_cmd() and it hasn't necessarily
> been NUL terminated.  We had not intended to read past "sensor_name_size"
> bytes, however, there is a width vs precision bug in the format string.
> The format needs to be precision '%.*s' instead of width '%*s'.
> Precision prevents an out of bounds read, but width is a no-op.
> 
> Fixes: bc3e45258096 ("hwmon: add ChromeOS EC driver")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

Acked-by: Thomas Weißschuh <linux@weissschuh.net>

devm_kstrndup() would have been nice.


Thomas

On 6/6/24 06:12, Dan Carpenter wrote:
> The "resp.sensor_name" comes from cros_ec_cmd() and it hasn't necessarily
> been NUL terminated.  We had not intended to read past "sensor_name_size"
> bytes, however, there is a width vs precision bug in the format string.
> The format needs to be precision '%.*s' instead of width '%*s'.
> Precision prevents an out of bounds read, but width is a no-op.
> 
> Fixes: bc3e45258096 ("hwmon: add ChromeOS EC driver")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>   drivers/hwmon/cros_ec_hwmon.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
> index 41f268fa8260..b3ba7247e06b 100644
> --- a/drivers/hwmon/cros_ec_hwmon.c
> +++ b/drivers/hwmon/cros_ec_hwmon.c
> @@ -212,7 +212,7 @@ static void cros_ec_hwmon_probe_temp_sensors(struct device *dev, struct cros_ec_
>   			continue;
>   
>   		sensor_name_size = strnlen(resp.sensor_name, sizeof(resp.sensor_name));
> -		priv->temp_sensor_names[i] = devm_kasprintf(dev, GFP_KERNEL, "%*s",
> +		priv->temp_sensor_names[i] = devm_kasprintf(dev, GFP_KERNEL, "%.*s",
>   							    (int)sensor_name_size,
>   							    resp.sensor_name);
>   	}