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

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Message-ID: <CAFhGd8rY5uTh+e0U8jG94dga6Acx5R1G+MKWt=LfD5orNNca+Q@mail.gmail.com>
Date:   Wed, 27 Sep 2023 23:05:07 +0900
From:   Justin Stitt <justinstitt@...gle.com>
To:     Guenter Roeck <linux@...ck-us.net>
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 Wed, Sep 27, 2023 at 9:49 PM Guenter Roeck <linux@...ck-us.net> wrote:
>
> 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.

Whoops, I was using some tooling to auto-fetch prefixes and the style
of "xyz: (stuff in paren)" isn't always caught.

I will resend with a fixed subject line matching the appropriate driver.

>
> Guenter

Thanks
Justin