linux-hardening - Re: [PATCH] accel/ivpu: refactor deprecated strncpy

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Date:   Fri, 25 Aug 2023 11:12:20 +0200
From:   Stanislaw Gruszka <stanislaw.gruszka@...ux.intel.com>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     Jacek Lawrynowicz <jacek.lawrynowicz@...ux.intel.com>,
        Oded Gabbay <ogabbay@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH] accel/ivpu: refactor deprecated strncpy

On Thu, Aug 24, 2023 at 09:20:25PM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on its destination buffer argument which is
> _not_ the case for `strncpy`!
> 
> Also remove extraneous if-statement as it can never be entered. The
> return value from `strncpy` is it's first argument. In this case,
> `...dyndbg_cmd` is an array:
> | 	char dyndbg_cmd[VPU_DYNDBG_CMD_MAX_LEN];
>              ^^^^^^^^^^
> This can never be NULL which means `strncpy`'s return value cannot be
> NULL here. Just use `strscpy` which is more robust and results in
> simpler and less ambiguous code.
> 
> Moreover, remove needless `... - 1` as `strscpy`'s implementation
> ensures NUL-termination and we do not need to carefully dance around
> ending boundaries with a "- 1" anymore.
> 
> Link: 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>
Applied to drm-misc-next-fixes

Thanks
Stanislaw