linux-kernel - Re: [PATCH] hwmon: (cros_ec) Prevent read overflow in probe()

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Date: Thu, 6 Jun 2024 07:05:22 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Dan Carpenter <dan.carpenter@...aro.org>,
 Thomas Weißschuh <linux@...ssschuh.net>
Cc: Thomas Weißschuh <thomas@...ssschuh.net>,
 Jean Delvare <jdelvare@...e.com>, Benson Leung <bleung@...omium.org>,
 Tzung-Bi Shih <tzungbi@...nel.org>, chrome-platform@...ts.linux.dev,
 linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
 kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] hwmon: (cros_ec) Prevent read overflow in probe()

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@...aro.org>

Reviewed-by: Guenter Roeck <linux@...ck-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);
>   	}