From: Kees Cook <keescook@chromium.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Alexander Potapenko <glider@google.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] kasan: test: Bypass __alloc_size checks
Date: Wed, 6 Oct 2021 09:33:18 -0700 [thread overview]
Message-ID: <202110060932.0808BD6500@keescook> (raw)
In-Reply-To: <20211006113732.GA14159@C02TD0UTHF1T.local>
On Wed, Oct 06, 2021 at 12:38:36PM +0100, Mark Rutland wrote:
> Hi Kees,
>
> On Tue, Oct 05, 2021 at 08:55:22PM -0700, Kees Cook wrote:
> > Intentional overflows, as performed by the KASAN tests, are detected
> > at compile time[1] (instead of only at run-time) with the addition of
> > __alloc_size. Fix this by forcing the compiler into not being able to
> > trust the size used following the kmalloc()s.
>
> It might be better to use OPTIMIZER_HIDE_VAR(), since that's intended to
> make the value opaque to the compiler, and volatile might not always do
> that depending on how the compiler tracks the variable.
Given both you and Jann[1] have suggested this, I'll send a v2 with that.
:) Thanks!
-Kees
[1] https://lore.kernel.org/lkml/CAG48ez19raco+s+UF8eiXqTvaDEoMAo6_qmW2KdO24QDpmZpFQ@mail.gmail.com/
--
Kees Cook
prev parent reply other threads:[~2021-10-06 16:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-06 3:55 [PATCH] kasan: test: Bypass __alloc_size checks Kees Cook
2021-10-06 11:38 ` Mark Rutland
2021-10-06 16:33 ` Kees Cook [this message]
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