linux-kernel - Re: [PATCH] net: ax88796c: replace deprecated strncpy with strscpy

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Message-ID: <202310042155.BDF8674@keescook>
Date:   Wed, 4 Oct 2023 21:55:48 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     Łukasz Stelmach <l.stelmach@...sung.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] net: ax88796c: replace deprecated strncpy with strscpy

On Thu, Oct 05, 2023 at 01:06:26AM +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.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding.
> 
> It should be noted that there doesn't currently exist a bug here as
> DRV_NAME is a small string literal which means no overread bugs are
> present.
> 
> Also to note, other ethernet drivers are using strscpy in a similar
> pattern:
> |       dec/tulip/tulip_core.c
> |       861:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       8390/ax88796.c
> |       582:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       dec/tulip/dmfe.c
> |       1077:   strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       8390/etherh.c
> |       558:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> 
> 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>

Yeah, this looks like the others.

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

-- 
Kees Cook