linux-kernel - Re: [PATCH v3] hwmon: refactor deprecated strncpy

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Message-ID: <9837d8dd-d802-4d5d-bca7-6e029658ba76@roeck-us.net>
Date:   Wed, 27 Sep 2023 05:48:56 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v3] hwmon: refactor deprecated strncpy

On Thu, Sep 21, 2023 at 05:41:46AM +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.
> 
> To avoid truncating the last byte supply `...length + 1` to
> kmemdup_nul() as `element->string.length` does not account for the
> trailing null as made obvious from it's definition (and associated
> comment):
> |       u32 length;	/* # of bytes in string, excluding trailing null */
> 
> ... this is precisely what the original kcalloc invocation did as well.
> 
> 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: linux-hardening@...r.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>

I have multiple patches with the hwmon: prefix but no driver,
like this one, suggesting the change is in the hwmon core,
when in reality it is in some hwmon driver.
I am not going to apply any of those, and I am not even going to
look into them.

Guenter