linux-kernel - Re: [RFC] selftests/x86: Add test

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Message-ID: <20180105191000.n2gnkbsyry4kd65z@pd.tnic>
Date:   Fri, 5 Jan 2018 20:10:00 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [RFC] selftests/x86: Add test_vsyscall

On Fri, Jan 05, 2018 at 10:45:49AM -0800, Andy Lutomirski wrote:
> Not _PAGE_RW.  Probably _PAGE_USER somewhere in the hierarchy.

Yeah, just realized that. But it must be somewhere in the PT hierarchy
because:

0xffffffffff600000-0xffffffffff601000           4K USR ro                     NX pte

So something up needs to take _PAGE_USER too.

But WTF does it say NX there for and still can execute the vsyscall
test? Oh boy, what a mess...

-- 
Regards/Gruss,
    Boris.

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