linux-kernel - Re: [PATCH] bcm63xx_enet: replace deprecated strncpy with strscpy

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Message-ID: <202310051544.822967F55@keescook>
Date:   Thu, 5 Oct 2023 15:46:08 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     "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] bcm63xx_enet: replace deprecated strncpy with strscpy

On Thu, Oct 05, 2023 at 08:51:40PM +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.
> 
> bcm_enet_get_drvinfo() already uses strscpy(), let's match it's
> implementation:
> |       static void bcm_enet_get_drvinfo(struct net_device *netdev,
> |       				 struct ethtool_drvinfo *drvinfo)
> |       {
> |       	strscpy(drvinfo->driver, bcm_enet_driver_name, sizeof(drvinfo->driver));
> |       	strscpy(drvinfo->bus_info, "bcm63xx", sizeof(drvinfo->bus_info));
> |       }
> 
> Note that now bcm_enet_get_drvinfo() and bcm_enetsw_get_drvinfo() do the
> exact same thing.
> 
> 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>

Looks good. Other writers to drvinfo, as you saw, do the same strscpy,
so this looks correct to me.

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

-- 
Kees Cook