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Message-ID: <6338fbac-0177-43eb-be4f-7c586956953f@kernel.dk>
Date:   Fri, 15 Sep 2023 07:36:40 -0600
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Subject: Re: [PATCH] aoe: refactor deprecated strncpy
Content-Language: en-US
To:     Kees Cook <keescook@chromium.org>,
        Justin Stitt <justinstitt@google.com>
Cc:     Justin Sanders <justin@coraid.com>, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org,
        Xu Panda <xu.panda@zte.com.cn>, Yang Yang <yang.yang29@zte.com>
References: <20230911-strncpy-drivers-block-aoe-aoenet-c-v1-1-9643d6137ff9@google.com>
 <202309142019.23A7D80A@keescook>
From:   Jens Axboe <axboe@kernel.dk>
In-Reply-To: <202309142019.23A7D80A@keescook>
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On 9/14/23 9:21 PM, Kees Cook wrote:
> On Mon, Sep 11, 2023 at 09:09:07PM +0000, Justin Stitt wrote:
>> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>>
>> `aoe_iflist` is expected to be NUL-terminated which is evident by its
>> use with string apis later on like `strspn`:
>> | 	p = aoe_iflist + strspn(aoe_iflist, WHITESPACE);
>>
>> It also seems `aoe_iflist` does not need to be NUL-padded which means
>> `strscpy` [2] is a suitable replacement due to the fact that it
>> guarantees NUL-termination on the destination buffer while not
>> 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
>> Cc: Kees Cook <keescook@chromium.org>
>> Cc: Xu Panda <xu.panda@zte.com.cn>
>> Cc: Yang Yang <yang.yang29@zte.com>
>> Signed-off-by: Justin Stitt <justinstitt@google.com>
> 
> Agreed, truncation is the current behavior, and padding isn't needed.
> (Or more precisely, it's already zeroed and this function is called
> once.)
> 
> Reviewed-by: Kees Cook <keescook@chromium.org>

Change looks fine to me too, but for the love of $deity, please use
a proper subject line for these kinds of patches. It's not refactoring
anything.

-- 
Jens Axboe