Date: Mon, 30 May 2011 09:46:08 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Andy Lutomirski <luto@MIT.EDU>
Cc: x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org, Jesper Juhl <jj@chaosbits.net>,
        Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Arjan van de Ven <arjan@infradead.org>,
        Jan Beulich <JBeulich@novell.com>,
        richard -rw- weinberger <richard.weinberger@gmail.com>,
        Mikael Pettersson <mikpe@it.uu.se>
Subject: Re: [PATCH v2 08/10] x86-64: Emulate vsyscalls
Message-ID: <20110530074608.GD27557@elte.hu>
References: <cover.1306724657.git.luto@mit.edu>
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* Andy Lutomirski <luto@MIT.EDU> wrote:

> There's a fair amount of code in the vsyscall page, and who knows
> what will happen if an exploit jumps into the middle of it.  Reduce
> the risk by replacing most of it with short magic incantations that
> are useless if entered in the middle.  This change can be disabled
> by CONFIG_UNSAFE_VSYSCALLS (default y).

btw., please flip the default or consider removing the option 
altogether.

We want to improve security and we want safe vsyscalls the default, 
and it's no good if we make it too easy for users to keep the fire 
door open all the time! :-)

Thanks,

	Ingo
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