[PATCH v2] hwmon: (ibmpowernv) refactor deprecated strncpy

[PATCH v2] hwmon: (ibmpowernv) refactor deprecated strncpy

[Justin Stitt]

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

A suitable replacement is `memcpy` as we've already precisely calculated
the number of bytes to copy while `buf` has been explicitly
zero-initialized:
| 	char buf[8] = { 0 };

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>
---
Changes in v2:
- prefer memcpy to strscpy (thanks Kees)
- Link to v1: https://lore.kernel.org/r/20230914-strncpy-drivers-hwmon-ibmpowernv-c-v1-1-ba6b7f42c98c@google.com
---
 drivers/hwmon/ibmpowernv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/ibmpowernv.c b/drivers/hwmon/ibmpowernv.c
index 594254d6a72d..70ca833259ab 100644
--- a/drivers/hwmon/ibmpowernv.c
+++ b/drivers/hwmon/ibmpowernv.c
@@ -234,7 +234,7 @@ static int get_sensor_index_attr(const char *name, u32 *index, char *attr)
 	if (copy_len >= sizeof(buf))
 		return -EINVAL;
 
-	strncpy(buf, hash_pos + 1, copy_len);
+	memcpy(buf, hash_pos + 1, copy_len);
 
 	err = kstrtou32(buf, 10, index);
 	if (err)

---
base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec
change-id: 20230914-strncpy-drivers-hwmon-ibmpowernv-c-80a03f16d93a

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

Re: [PATCH v2] hwmon: (ibmpowernv) refactor deprecated strncpy

[Michael Ellerman]

Justin Stitt <justinstitt@google.com> writes:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> A suitable replacement is `memcpy` as we've already precisely calculated
> the number of bytes to copy while `buf` has been explicitly
> zero-initialized:
> | 	char buf[8] = { 0 };
>
> 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>
> ---
> Changes in v2:
> - prefer memcpy to strscpy (thanks Kees)
> - Link to v1: https://lore.kernel.org/r/20230914-strncpy-drivers-hwmon-ibmpowernv-c-v1-1-ba6b7f42c98c@google.com
> ---
>  drivers/hwmon/ibmpowernv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

cheers

Re: [PATCH v2] hwmon: (ibmpowernv) refactor deprecated strncpy

[Kees Cook]

On Tue, 19 Sep 2023 05:22:51 +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> A suitable replacement is `memcpy` as we've already precisely calculated
> the number of bytes to copy while `buf` has been explicitly
> zero-initialized:
> | 	char buf[8] = { 0 };
> 
> [...]

Applied to for-next/hardening, thanks! (I've updated the Subject here
and with the older "refactor" subjects...)

Take care,

-- 
Kees Cook