netdev - Re: [PATCH] ibmvnic: replace deprecated strncpy with strscpy

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Message-ID: <202310101551.DAE933A@keescook>
Date: Tue, 10 Oct 2023 15:51:23 -0700
From: Kees Cook <keescook@...omium.org>
To: Justin Stitt <justinstitt@...gle.com>
Cc: Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Haren Myneni <haren@...ux.ibm.com>,
	Rick Lindsley <ricklind@...ux.ibm.com>,
	Nick Child <nnac123@...ux.ibm.com>,
	Dany Madden <danymadden@...ibm.com>,
	Thomas Falcon <tlfalcon@...ux.ibm.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	linuxppc-dev@...ts.ozlabs.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] ibmvnic: replace deprecated strncpy with strscpy

On Mon, Oct 09, 2023 at 11:19:57PM +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.
> 
> NUL-padding is not required as the buffer is already memset to 0:
> |       memset(adapter->fw_version, 0, 32);
> 
> Note that another usage of strscpy exists on the same buffer:
> |       strscpy((char *)adapter->fw_version, "N/A", sizeof(adapter->fw_version));
> 
> Considering the above, a suitable replacement is `strscpy` [2] due to
> the fact that it guarantees NUL-termination on the destination buffer
> without unnecessarily NUL-padding.
> 
> 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>

Thanks, this looks right to me.

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

-- 
Kees Cook