linux-kernel - Re: [PATCH 3/3] lkdtm: Check for SMEP clearing protections

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Message-ID: <CAGXu5jJpeh5Ark4QG-UMUUkr-d+hWoBBb5eYzoGOCFXnW3xgkw@mail.gmail.com>
Date:   Tue, 26 Feb 2019 15:40:34 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Jann Horn <jannh@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] lkdtm: Check for SMEP clearing protections

On Tue, Feb 26, 2019 at 3:37 PM Kees Cook <keescook@...omium.org> wrote:
> +       for (i = 0; i < 64; i++) {
> ...
> +       }
> +       if (i >= 256) {
> +               pr_info("ok: cannot locate cr4 writing call gadget\n");
> +               return;
> +       }

*brown paper bag*
Argh. I changed the depth of that search at the last moment and now
it's mismatched. *sigh* I will send a v2 for this with it fixed.

-- 
Kees Cook