linux-hardening - Re: [PATCH v2] net: ena: replace deprecated strncpy with strscpy

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Date: Fri, 8 Dec 2023 09:22:55 -0800
From: Kees Cook <keescook@...omium.org>
To: justinstitt@...gle.com
Cc: Shay Agroskin <shayagr@...zon.com>,
	Arthur Kiyanovski <akiyano@...zon.com>,
	David Arinzon <darinzon@...zon.com>, Noam Dagan <ndagan@...zon.com>,
	Saeed Bishara <saeedb@...zon.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] net: ena: replace deprecated strncpy with strscpy

On Thu, Dec 07, 2023 at 09:34:42PM +0000, justinstitt@...gle.com 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.
> 
> host_info allocation is done in ena_com_allocate_host_info() via
> dma_alloc_coherent() and is not zero initialized by alloc_etherdev_mq().
> 
> However zero initialization of the destination doesn't matter in this case,
> because strscpy() guarantees a NULL termination.
> 
> 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 reads much better.

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

-- 
Kees Cook