Date: Sat, 22 Aug 2015 11:05:19 +0200
From: Borislav Petkov <bp@suse.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: yalin wang <yalin.wang2010@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>, mingo@redhat.com, x86@kernel.org,
        open list <linux-kernel@vger.kernel.org>,
        Will Deacon <will.deacon@arm.com>
Subject: Re: [x86] copy_from{to}_user question
Message-ID: <20150822090519.GA2812@nazgul.tnic>
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 <9232AF8E-87A3-40B2-852A-D07889F9E1B4@gmail.com>
 <20150813164302.GA15881@nazgul.tnic>
 <6ABF6137-251E-47EF-B824-AC77C9C9AB24@gmail.com>
 <20150817041634.GA9387@nazgul.tnic>
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On Fri, Aug 21, 2015 at 02:06:16PM -0700, H. Peter Anvin wrote:
> What I'm saying is that we do do STAC, which *disables* SMAP.  We have
> to do that because one pointer is known to be a user space pointer.
> 
> However, we currently don't verify that the *other* pointer is kernel
> space, which it is supposed to be (if not, we should be using
> copy_in_user).  We have to do this manually since we have to STAC which
> means SMAP doesn't do anything at all.  I believe it would be a good
> idea to add such checks (and they would even benefit non-SMAP hardware.)

Ah, ok, so we're on the same page.

And yep, Linus gave the probe_kernel_read() suggestion in another mail.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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