From mboxrd@z Thu Jan  1 00:00:00 1970
From: bsingharora@gmail.com (Balbir Singh)
Date: Wed, 20 Jul 2016 20:24:43 +1000
Subject: [PATCH v3 02/11] mm: Hardened usercopy
In-Reply-To: <CAGXu5j+nHpHcYT8FyHNe6AFQCdakoSMW=UWDatyxhRK7CB7_=g@mail.gmail.com>
References: <1468619065-3222-1-git-send-email-keescook@chromium.org>
 <1468619065-3222-3-git-send-email-keescook@chromium.org>
 <fc3c7f68-bd2e-cb06-c47c-d97c520fc08b@redhat.com>
 <CAGXu5j+nHpHcYT8FyHNe6AFQCdakoSMW=UWDatyxhRK7CB7_=g@mail.gmail.com>
Message-ID: <1469010283.2800.5.camel@gmail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Tue, 2016-07-19 at 11:48 -0700, Kees Cook wrote:
> On Mon, Jul 18, 2016 at 6:06 PM, Laura Abbott <labbott@redhat.com> wrote:
> >?
> > On 07/15/2016 02:44 PM, Kees Cook wrote:
> >?
> > This doesn't work when copying CMA allocated memory since CMA purposely
> > allocates larger than a page block size without setting head pages.
> > Given CMA may be used with drivers doing zero copy buffers, I think it
> > should be permitted.
> >?
> > Something like the following lets it pass (I can clean up and submit
> > the is_migrate_cma_page APIs as a separate patch for review)
> Yeah, this would be great. I'd rather use an accessor to check this
> than a direct check for MIGRATE_CMA.
>
> > ?????????*/
> > ????????for (; ptr <= end ; ptr += PAGE_SIZE, page = virt_to_head_page(ptr))
> > {
> > -???????????????if (!PageReserved(page))
> > +???????????????if (!PageReserved(page) && !is_migrate_cma_page(page))
> > ????????????????????????return "<spans multiple pages>";
> > ????????}
> Yeah, I'll modify this a bit so that which type it starts as is
> maintained for all pages (rather than allowing to flip back and forth
> -- even though that is likely impossible).
>?
Sorry, I completely missed the MIGRATE_CMA bits. Could you clarify if you
caught this in testing/review?

Balbir Singh.