linux-kernel - Re: [PATCH v2] bna: replace deprecated strncpy with strscpy

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Message-ID: <202310091258.C4CDBBED7D@keescook>
Date:   Mon, 9 Oct 2023 12:58:32 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     Rasesh Mody <rmody@...vell.com>,
        Sudarsana Kalluru <skalluru@...vell.com>,
        GR-Linux-NIC-Dev@...vell.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 v2] bna: replace deprecated strncpy with strscpy_pad

On Mon, Oct 09, 2023 at 05:45:33PM +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.
> 
> bfa_ioc_get_adapter_manufacturer() simply copies a string literal into
> `manufacturer`.
> 
> Another implementation of bfa_ioc_get_adapter_manufacturer() from
> drivers/scsi/bfa/bfa_ioc.c uses memset + strscpy:
> |	void
> |	bfa_ioc_get_adapter_manufacturer(struct bfa_ioc_s *ioc, char *manufacturer)
> |	{
> |		memset((void *)manufacturer, 0, BFA_ADAPTER_MFG_NAME_LEN);
> |			strscpy(manufacturer, BFA_MFG_NAME, BFA_ADAPTER_MFG_NAME_LEN);
> |	}
> 
> Let's use `strscpy_pad` to eliminate some redundant work while still
> NUL-terminating and NUL-padding the destination buffer.
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@...r.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>

Thanks for the update! Yeah, this looks safe to me now.

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

-- 
Kees Cook