[PATCH] thermal: core: Use strnlen in thermal_zone_device_register_with_trips

[PATCH] thermal: core: Use strnlen in thermal_zone_device_register_with_trips

[Thorsten Blum]

Replace strlen() with the safer strnlen() and calculate the length of
the thermal zone name 'type' only once.  No functional changes.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 drivers/thermal/thermal_core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 17ca5c082643..63eb35b449c6 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -1505,15 +1505,17 @@ thermal_zone_device_register_with_trips(const char *type,
 	const struct thermal_trip *trip = trips;
 	struct thermal_zone_device *tz;
 	struct thermal_trip_desc *td;
+	size_t type_len;
 	int id;
 	int result;
 
-	if (!type || strlen(type) == 0) {
+	type_len = type ? strnlen(type, THERMAL_NAME_LENGTH) : 0;
+	if (type_len == 0) {
 		pr_err("No thermal zone type defined\n");
 		return ERR_PTR(-EINVAL);
 	}
 
-	if (strlen(type) >= THERMAL_NAME_LENGTH) {
+	if (type_len == THERMAL_NAME_LENGTH) {
 		pr_err("Thermal zone name (%s) too long, should be under %d chars\n",
 		       type, THERMAL_NAME_LENGTH);
 		return ERR_PTR(-EINVAL);
-- 
Thorsten Blum <thorsten.blum@linux.dev>
GPG: 1D60 735E 8AEF 3BE4 73B6  9D84 7336 78FD 8DFE EAD4

Re: [PATCH] thermal: core: Use strnlen in thermal_zone_device_register_with_trips

[Rafael J. Wysocki]

On Mon, Dec 15, 2025 at 1:16 PM Thorsten Blum <thorsten.blum@linux.dev> wrote:
>
> Replace strlen() with the safer strnlen() and calculate the length of
> the thermal zone name 'type' only once.  No functional changes.
>
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
>  drivers/thermal/thermal_core.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 17ca5c082643..63eb35b449c6 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1505,15 +1505,17 @@ thermal_zone_device_register_with_trips(const char *type,
>         const struct thermal_trip *trip = trips;
>         struct thermal_zone_device *tz;
>         struct thermal_trip_desc *td;
> +       size_t type_len;

size_t type_len = 0;

>         int id;
>         int result;
>
> -       if (!type || strlen(type) == 0) {
> +       type_len = type ? strnlen(type, THERMAL_NAME_LENGTH) : 0;

if (type)
        type_len = strnlen(type, THERMAL_NAME_LENGTH);

Pretty please.

> +       if (type_len == 0) {
>                 pr_err("No thermal zone type defined\n");
>                 return ERR_PTR(-EINVAL);
>         }
>
> -       if (strlen(type) >= THERMAL_NAME_LENGTH) {
> +       if (type_len == THERMAL_NAME_LENGTH) {
>                 pr_err("Thermal zone name (%s) too long, should be under %d chars\n",
>                        type, THERMAL_NAME_LENGTH);
>                 return ERR_PTR(-EINVAL);
> --