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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed, 28 Jun 2023 21:35:49 -0700
Message-ID: <CAHk-=whbbFHUF44At4YYOB9ZWg00rhFmyArD+KocXDX-+-8a1Q@mail.gmail.com>
Subject: Re: Build error in crypto/marvell/cesa/cipher.c
To:     Kees Cook <keescook@chromium.org>
Cc:     Boris Brezillon <bbrezillon@kernel.org>,
        Arnaud Ebalard <arno@natisbad.org>,
        Srujana Challa <schalla@marvell.com>,
        Mustafa Ismail <mustafa.ismail@intel.com>,
        Shiraz Saleem <shiraz.saleem@intel.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Leon Romanovsky <leon@kernel.org>
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On Wed, 28 Jun 2023 at 20:48, Kees Cook <keescook@chromium.org> wrote:
>
> The unexpected bit is that without -fstrict-flex-arrays=3 (i.e. the
> default since the dawn of time), the compiler treats any array that
> happens to be the last struct member as a flexible array.

Oh. Ok, that explains why it's showing up for me now, at least. It's
an odd rule, but I can see why people would have done that.

I've only seen the zero- and one-sized arrays commonly used for the
traditional "fake flex array", but I guess other sizes can easily
happen.

                 Linus