Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 6 Oct 2020 01:44:14 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Jann Horn <jannh@google.com>
Cc:     Alexander Popov <alex.popov@linux.com>,
        Kees Cook <keescook@chromium.org>,
        Will Deacon <will@kernel.org>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Patrick Bellasi <patrick.bellasi@arm.com>,
        David Howells <dhowells@redhat.com>,
        Eric Biederman <ebiederm@xmission.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Laura Abbott <labbott@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Daniel Micay <danielmicay@gmail.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        Pavel Machek <pavel@denx.de>,
        Valentin Schneider <valentin.schneider@arm.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux-MM <linux-mm@kvack.org>,
        Kernel Hardening <kernel-hardening@lists.openwall.com>,
        kernel list <linux-kernel@vger.kernel.org>, notify@kernel.org
Subject: Re: [PATCH RFC v2 0/6] Break heap spraying needed for exploiting
 use-after-free
Message-ID: <20201006004414.GP20115@casper.infradead.org>
References: <20200929183513.380760-1-alex.popov@linux.com>
 <91d564a6-9000-b4c5-15fd-8774b06f5ab0@linux.com>
 <CAG48ez1tNU_7n8qtnxTYZ5qt-upJ81Fcb0P2rZe38ARK=iyBkA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAG48ez1tNU_7n8qtnxTYZ5qt-upJ81Fcb0P2rZe38ARK=iyBkA@mail.gmail.com>
Precedence: bulk

On Tue, Oct 06, 2020 at 12:56:33AM +0200, Jann Horn wrote:
> It seems to me like, if you want to make UAF exploitation harder at
> the heap allocator layer, you could do somewhat more effective things
> with a probably much smaller performance budget. Things like
> preventing the reallocation of virtual kernel addresses with different
> types, such that an attacker can only replace a UAF object with
> another object of the same type. (That is not an idea I like very much
> either, but I would like it more than this proposal.) (E.g. some
> browsers implement things along those lines, I believe.)

The slab allocator already has that functionality.  We call it
TYPESAFE_BY_RCU, but if forcing that on by default would enhance security
by a measurable amount, it wouldn't be a terribly hard sell ...