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Date:   Mon, 22 Jul 2019 21:35:27 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Joe Perches <joe@perches.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        Stephen Kitt <steve@sk2.org>,
        Kees Cook <keescook@chromium.org>,
        Nitin Gote <nitin.r.gote@intel.com>, jannh@google.com,
        kernel-hardening@lists.openwall.com,
        Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Subject: Re: [PATCH 1/2] string: Add stracpy and stracpy_pad mechanisms
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On Mon, 22 Jul 2019 17:38:15 -0700 Joe Perches <joe@perches.com> wrote:

> Several uses of strlcpy and strscpy have had defects because the
> last argument of each function is misused or typoed.
> 
> Add macro mechanisms to avoid this defect.
> 
> stracpy (copy a string to a string array) must have a string
> array as the first argument (to) and uses sizeof(to) as the
> size.
> 
> These mechanisms verify that the to argument is an array of
> char or other compatible types like u8 or unsigned char.
> 
> A BUILD_BUG is emitted when the type of to is not compatible.
> 

It would be nice to include some conversions.  To demonstrate the need,
to test the code, etc.