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Date: Thu, 28 Mar 2024 21:04:50 -0700
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/hdmi: prefer length specifier in format over
 string copying
Message-ID: <202403282104.CC17451@keescook>
References: <20240320-strncpy-drivers-video-hdmi-c-v1-1-f9a08168cdaf@google.com>
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In-Reply-To: <20240320-strncpy-drivers-video-hdmi-c-v1-1-f9a08168cdaf@google.com>

On Wed, Mar 20, 2024 at 11:22:02PM +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.
> 
> It looks like the main use of strncpy() here is to limit the amount of
> bytes printed from hdmi_log() by using a tmp buffer and limiting the
> number of bytes copied. Really, we should use the %.<len>s format
> qualifier to achieve this.
> 
> 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
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

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

-- 
Kees Cook