2023-09-26 16:16:43

by Justin Stitt

Subject: [PATCH v5] hwmon: (acpi_power_meter) replace open-coded kmemdup_nul

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

Let's refactor this kcalloc() + strncpy() into a kmemdup_nul() which has
more obvious behavior and is less error prone.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Changes in v5:
- fix indentation (thanks Kees)
- Link to v4: https://lore.kernel.org/r/20230925-strncpy-drivers-hwmon-acpi_power_meter-c-v4-1-3bac7534f10f@google.com

Changes in v4:
- drop +1 from length arg (thanks Kees)
- reword subject line (thanks Kees)
- rebase onto 6465e260f4879080
- Link to v3: https://lore.kernel.org/r/20230921-strncpy-drivers-hwmon-acpi_power_meter-c-v3-1-307552c6ec3f@google.com

Changes in v3:
- refactor to use kmemdup_nul() (thanks Thomas and Kees)
- change commit msg to reflect ^
- rebase onto 2cf0f71562387282
- Link to v2: https://lore.kernel.org/r/20230919-strncpy-drivers-hwmon-acpi_power_meter-c-v2-1-8348432d6442@google.com

Changes in v2:
- use memcpy over strscpy (thanks Kees)
- Link to v1: https://lore.kernel.org/r/20230914-strncpy-drivers-hwmon-acpi_power_meter-c-v1-1-905297479fe8@google.com
---
drivers/hwmon/acpi_power_meter.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/acpi_power_meter.c b/drivers/hwmon/acpi_power_meter.c
index fa28d447f0df..8db740214ffd 100644
--- a/drivers/hwmon/acpi_power_meter.c
+++ b/drivers/hwmon/acpi_power_meter.c
@@ -796,14 +796,13 @@ static int read_capabilities(struct acpi_power_meter_resource *resource)
goto error;
}

- *str = kcalloc(element->string.length + 1, sizeof(u8),
- GFP_KERNEL);
+ *str = kmemdup_nul(element->string.pointer, element->string.length,
+ GFP_KERNEL);
if (!*str) {
res = -ENOMEM;
goto error;
}

- strncpy(*str, element->string.pointer, element->string.length);
str++;
}


---
base-commit: 6465e260f48790807eef06b583b38ca9789b6072
change-id: 20230914-strncpy-drivers-hwmon-acpi_power_meter-c-c9f2d8053bef

Best regards,
--
Justin Stitt <[email protected]>

2023-10-02 17:51:11

by Kees Cook

Subject: Re: [PATCH v5] hwmon: (acpi_power_meter) replace open-coded kmemdup_nul

On Tue, Sep 26, 2023 at 06:59:15AM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> Let's refactor this kcalloc() + strncpy() into a kmemdup_nul() which has
> more obvious behavior and is less error prone.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>

Thanks for continue to rev this change. This looks much nicer, is more
readable, etc. :)

Reviewed-by: Kees Cook <[email protected]>

--
Kees Cook

2023-10-24 21:19:54

by Kees Cook

Subject: Re: [PATCH v5] hwmon: (acpi_power_meter) replace open-coded kmemdup_nul

On Tue, 26 Sep 2023 06:59:15 +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> Let's refactor this kcalloc() + strncpy() into a kmemdup_nul() which has
> more obvious behavior and is less error prone.
>
>

Applied to for-next/hardening, thanks!

[1/1] hwmon: (acpi_power_meter) replace open-coded kmemdup_nul
https://git.kernel.org/kees/c/9cca73d7b4bf

Take care,

--
Kees Cook