[PATCH] hwmon: (asus_wmi_sensors) refactor deprecated strncpy

[PATCH] hwmon: (asus_wmi_sensors) refactor deprecated strncpy

[Justin Stitt]

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer without
unnecessarily NUL-padding. If, for any reason, NUL-padding is needed
let's opt for `strscpy_pad`.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
 drivers/hwmon/asus_wmi_sensors.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/asus_wmi_sensors.c b/drivers/hwmon/asus_wmi_sensors.c
index 6e8a908171f0..c2dd7ff882f2 100644
--- a/drivers/hwmon/asus_wmi_sensors.c
+++ b/drivers/hwmon/asus_wmi_sensors.c
@@ -300,7 +300,7 @@ static int asus_wmi_sensor_info(int index, struct asus_wmi_sensor_info *s)
 		goto out_free_obj;
 	}
 
-	strncpy(s->name, name_obj.string.pointer, sizeof(s->name) - 1);
+	strscpy(s->name, name_obj.string.pointer, sizeof(s->name));
 
 	data_type_obj = obj->package.elements[1];
 	if (data_type_obj.type != ACPI_TYPE_INTEGER) {

---
base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec
change-id: 20230914-strncpy-drivers-hwmon-asus_wmi_sensors-c-e10e094a467d

Best regards,
--
Justin Stitt <justinstitt@google.com>

Re: [PATCH] hwmon: (asus_wmi_sensors) refactor deprecated strncpy

[Kees Cook]

On Thu, Sep 14, 2023 at 11:10:34PM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> We should prefer more robust and less ambiguous string interfaces.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding. If, for any reason, NUL-padding is needed
> let's opt for `strscpy_pad`.
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

A classic replacement. :)

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH] hwmon: (asus_wmi_sensors) refactor deprecated strncpy

[Kees Cook]

On Thu, 14 Sep 2023 23:10:34 +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> We should prefer more robust and less ambiguous string interfaces.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding. If, for any reason, NUL-padding is needed
> let's opt for `strscpy_pad`.
> 
> [...]

Applied to for-next/hardening, thanks! (Subject updated...)

Take care,

-- 
Kees Cook