Re: [PATCH] net: dsa: realtek: replace deprecated strncpy with ethtool_sprintf

[Linus Walleij]

On Tue, Oct 10, 2023 at 12:47 AM Justin Stitt <justinstitt@xxxxxxxxxx> wrote:


> `strncpy` is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> ethtool_sprintf() is designed specifically for get_strings() usage.
> Let's replace strncpy in favor of this more robust and easier to
> understand interface.
>
> 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@xxxxxxxxxxxxxxx
> Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
(...)
> -               mib = &priv->mib_counters[i];
> -               strncpy(data + i * ETH_GSTRING_LEN,
> -                       mib->name, ETH_GSTRING_LEN);
> +               ethtool_sprintf(&data, "%s", priv->mib_counters[i].name);

Not only does it harden the kernel, it also makes it way easier to read!

Way to go.
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Yours,
Linus Walleij