netdev - Re: [PATCH v2] net: dsa: vsc73xx: replace deprecated strncpy with ethtool

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Message-ID: <202310101658.84E1C724@keescook>
Date: Tue, 10 Oct 2023 16:58:14 -0700
From: Kees Cook <keescook@...omium.org>
To: Justin Stitt <justinstitt@...gle.com>
Cc: Andrew Lunn <andrew@...n.ch>, Florian Fainelli <f.fainelli@...il.com>,
	Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] net: dsa: vsc73xx: replace deprecated strncpy with
 ethtool_sprintf

On Tue, Oct 10, 2023 at 10:32:35PM +0000, Justin Stitt 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.
> 
> This change could result in misaligned strings when if(cnt) fails. To
> combat this, use ternary to place empty string in buffer and properly
> increment pointer to next string slot.
> 
> 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@...r.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>

Nice; much more readable.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook