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Date:   Fri, 8 Dec 2023 09:22:55 -0800
From:   Kees Cook <keescook@chromium.org>
To:     justinstitt@google.com
Cc:     Shay Agroskin <shayagr@amazon.com>,
        Arthur Kiyanovski <akiyano@amazon.com>,
        David Arinzon <darinzon@amazon.com>,
        Noam Dagan <ndagan@amazon.com>,
        Saeed Bishara <saeedb@amazon.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2] net: ena: replace deprecated strncpy with strscpy
Message-ID: <202312080922.881A1515F3@keescook>
References: <20231207-strncpy-drivers-net-ethernet-amazon-ena-ena_netdev-c-v2-1-a1f2893d1b70@google.com>
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In-Reply-To: <20231207-strncpy-drivers-net-ethernet-amazon-ena-ena_netdev-c-v2-1-a1f2893d1b70@google.com>
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On Thu, Dec 07, 2023 at 09:34:42PM +0000, justinstitt@google.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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Yeah, this reads much better.

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

-- 
Kees Cook