Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 30 Jul 2021 12:18:26 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Dan Carpenter <dan.carpenter@oracle.com>, dsterba@suse.cz,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Bart Van Assche <bvanassche@acm.org>,
        linux-hardening@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Keith Packard <keithpac@amazon.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-staging@lists.linux.dev, linux-block@vger.kernel.org,
        linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com,
        nborisov@suse.com
Subject: Re: [PATCH 01/64] media: omap3isp: Extract struct group for memcpy()
 region
Message-ID: <202107301217.46EA9DA@keescook>
References: <20210728091434.GQ1931@kadam>
 <c52a52d9-a9e0-5020-80fe-4aada39035d3@acm.org>
 <20210728213730.GR5047@suse.cz>
 <YQJDCw01gSp1d1/M@kroah.com>
 <20210729082039.GX25548@kadam>
 <202107291952.C08EAE039B@keescook>
 <20210730083845.GD5047@suse.cz>
 <20210730090054.GX1931@kadam>
 <202107300937.C7016A82@keescook>
 <CAKwvOdmtKszUS0-OyGMHuhqjyXQC_283KOQOouWWtimYCvsAoA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAKwvOdmtKszUS0-OyGMHuhqjyXQC_283KOQOouWWtimYCvsAoA@mail.gmail.com>
Precedence: bulk

On Fri, Jul 30, 2021 at 10:08:03AM -0700, Nick Desaulniers wrote:
> On Fri, Jul 30, 2021 at 9:44 AM Kees Cook <keescook@chromium.org> wrote:
> >
> > On Fri, Jul 30, 2021 at 12:00:54PM +0300, Dan Carpenter wrote:
> > > On Fri, Jul 30, 2021 at 10:38:45AM +0200, David Sterba wrote:
> > > > Then is explicit memset the only reliable way accross all compiler
> > > > flavors and supported versions?
> > > >
> > >
> > > The = { } initializer works.  It's only when you start partially
> > > initializing the struct that it doesn't initialize holes.
> >
> > No, partial works. It's when you _fully_ initialize the struct where the
> > padding doesn't get initialized. *sob*
> 
> I'm pretty sure that this has more to do with whether or not the
> compiler applies SROA then observes uses of the individual members or
> not.

Ultimately, it's just not consistent, so thank goodness for
-ftrivial-auto-var-init=zero. :)

-- 
Kees Cook