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Date:   Tue, 10 Oct 2023 15:51:23 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Justin Stitt <justinstitt@google.com>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Haren Myneni <haren@linux.ibm.com>,
        Rick Lindsley <ricklind@linux.ibm.com>,
        Nick Child <nnac123@linux.ibm.com>,
        Dany Madden <danymadden@us.ibm.com>,
        Thomas Falcon <tlfalcon@linux.ibm.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linuxppc-dev@lists.ozlabs.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org
Subject: Re: [PATCH] ibmvnic: replace deprecated strncpy with strscpy
Message-ID: <202310101551.DAE933A@keescook>
References: <20231009-strncpy-drivers-net-ethernet-ibm-ibmvnic-c-v1-1-712866f16754@google.com>
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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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Thanks, this looks right to me.

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

-- 
Kees Cook