linux-kernel - Re: [PATCH v2 2/3] x86/ldt: Make modify

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Message-ID: <55AEA99C.3030608@oracle.com>
Date:	Tue, 21 Jul 2015 16:20:44 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>
CC:	"security@...nel.org" <security@...nel.org>,
	X86 ML <x86@...nel.org>, Borislav Petkov <bp@...en8.de>,
	linux-kernel@...r.kernel.org,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: Re: [PATCH v2 2/3] x86/ldt: Make modify_ldt optional

On 07/21/2015 03:59 PM, Andy Lutomirski wrote:
> The modify_ldt syscall exposes a large attack surface and is
> unnecessary for modern userspace.  Make it optional.

Since this a "default y" option I think we need to make the
implications of this a bit clearer.

Do we know what userspace would break?

Maybe add a WARN_ONCE() in a stub syscall?


Thanks,
Sasha
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