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Date: Thu, 6 Oct 2011 17:37:40 +0200
Message-ID: <CAFLxGvx0Cpu0ePytdCSSzfO2or3ZL3j5QrghOE5eWHZCJt6C6g@mail.gmail.com>
Subject: Re: [3.1 patch] x86: default to vsyscall=native
From: richard -rw- weinberger <richard.weinberger@gmail.com>
To: Andrew Lutomirski <luto@mit.edu>
Cc: Adrian Bunk <bunk@stusta.de>, "H. Peter Anvin" <hpa@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org
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On Thu, Oct 6, 2011 at 5:06 AM, Andrew Lutomirski <luto@mit.edu> wrote:
> I'll see how ugly the patch to get this all correct is. =A0It may not be
> all that pretty because we won't be able to use sys_gettimeofday
> anymore.

BTW: The attached program triggers the issue.

on 3.1-rc8+:
# ./sig.dyn
faulting address: 0xdeadbeef
# ./sig.static
[   19.075106] sig.static[863] vsyscall fault (exploit attempt?)
ip:ffffffffff600000 cs:33 sp:7fff9e53d8c8 ax:ffffffffff600000 si:0
di:deadbeef
faulting address: 0x0

I guess UML is not the only user of this feature...

--=20
Thanks,
//richard

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