Re: [PATCH] video: fbdev: au1200fb: replace deprecated strncpy with strscpy

From: Kees Cook <keescook@chromium.org>
To: Justin Stitt <justinstitt@google.com>
Cc: Helge Deller <deller@gmx.de>,
	linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] video: fbdev: au1200fb: replace deprecated strncpy with strscpy
Date: Tue, 19 Mar 2024 19:44:06 -0700	[thread overview]
Message-ID: <202403191944.B66E4853@keescook> (raw)
In-Reply-To: <20240318-strncpy-drivers-video-fbdev-au1200fb-c-v1-1-680802a9f10a@google.com>

On Mon, Mar 18, 2024 at 11:46:33PM +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.
> 
> Let's use the new 2-argument strscpy() which guarantees NUL-termination
> on the destination buffer while also simplifying the syntax. Note that
> strscpy() will not NUL-pad the destination buffer like strncpy() does.
> 
> However, the NUL-padding behavior of strncpy() is not required since
> fbdev is already NUL-allocated from au1200fb_drv_probe() ->
> frameuffer_alloc(), rendering any additional NUL-padding redundant.
> |	p = kzalloc(fb_info_size + size, GFP_KERNEL);
> 
> 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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Yup, looks correct.

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

-- 
Kees Cook