linux-hardening - Re: [PATCH v4] EDAC/mc_sysfs: refactor deprecated strncpy

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Message-ID: <202309231950.698026E687@keescook>
Date: Sat, 23 Sep 2023 19:51:58 -0700
From: Kees Cook <keescook@...omium.org>
To: Justin Stitt <justinstitt@...gle.com>
Cc: Borislav Petkov <bp@...en8.de>, Tony Luck <tony.luck@...el.com>,
	James Morse <james.morse@....com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Robert Richter <rric@...nel.org>, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v4] EDAC/mc_sysfs: refactor deprecated strncpy

On Mon, Sep 18, 2023 at 07:47:29AM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> We've already calculated bounds, possible truncation with '\0' or '\n'
> and manually NUL-terminated. The situation is now just a literal byte
> copy from one buffer to another, let's treat it as such and use a less
> ambiguous interface in memcpy.
> 
> 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>

Yeah, I think this looks good now. If a v5 is needed, a tiny improvement
would be to update the Subject: to "...: replace strncpy with memcpy".

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

-Kees

-- 
Kees Cook