Message-ID: <1478838308.11393.15.camel@redhat.com>
Subject: Re: [kernel-hardening] Re: [RFC v4 PATCH 00/13] HARDENED_ATOMIC
From: Rik van Riel <riel@redhat.com>
To: kernel-hardening@lists.openwall.com,
        Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>,
        Elena Reshetova <elena.reshetova@intel.com>,
        Arnd Bergmann <arnd@arndb.de>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <h.peter.anvin@intel.com>,
        LKML <linux-kernel@vger.kernel.org>
Date: Thu, 10 Nov 2016 23:25:08 -0500
In-Reply-To: <CAGXu5jJpOxewaYTOFRKBS-YmzAGDY++guVFYdQh8vsJLU4zJzA@mail.gmail.com>
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         <20161110203749.GV3117@twins.programming.kicks-ass.net>
         <20161110204838.GE17134@arm.com>
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         <CAGXu5jJpOxewaYTOFRKBS-YmzAGDY++guVFYdQh8vsJLU4zJzA@mail.gmail.com>
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On Thu, 2016-11-10 at 13:23 -0800, Kees Cook wrote:

> If we don't use opt-out for atomics, we're going to be in the same
> situation where we have to constantly review every commit with an
> atomic for exploitable refcount flaws. Kicking this down from
> "privilege escalation" to "DoS" is a significant change in the
> kernel's weaknesses.

The only way I see around that would be to totally get
rid of the name atomic_t, forcing people with out of
tree code to use kref_t, or whatever name we pick for
the variable type that can wrap.

Something like checkpatch or a patch checking bot
could warn whenever new code is submitted that uses
the counter type that can wrap.

Not sure whether I like my idea :)

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