linux-kernel - Re: [PATCH 00/11] x86: Supervisor Mode Access Prevention

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Message-ID: <505CC6B8.5000605@zytor.com>
Date:	Fri, 21 Sep 2012 12:57:44 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Kees Cook <keescook@...omium.org>,
	Linda Wang <lwang@...hat.com>,
	Matt Fleming <matt.fleming@...el.com>
Subject: Re: [PATCH 00/11] x86: Supervisor Mode Access Prevention

On 09/21/2012 12:54 PM, Linus Torvalds wrote:
> On Fri, Sep 21, 2012 at 12:43 PM, H. Peter Anvin <hpa@...ux.intel.com> wrote:
>> Supervisor Mode Access Prevention (SMAP) is a new security feature
>> disclosed by Intel in revision 014 of the Intel® Architecture
>> Instruction Set Extensions Programming Reference:
> 
> Looks good.
> 
> Did this find any bugs, btw? We've had a few cases where we forgot to
> use the proper user access function, and code just happened to work
> because it all boils down to the same thing and never got any page
> faults in practice anyway..
> 
> I'd obviously hope that we have caught all of them, but.. IOW, has
> SMAP actually triggered for anybody in testing inside Intel?
> 

So far, it caught the use of PAGE_READONLY instead of PAGE_KERNEL_RO for
the WP test on 32 bits (patch 02/11).

It has not had very high testing bandwidth yet, and especially the
exposure of driver code has been very limited, so I would not be at all
surprised if more crop up.

	-hpa
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