linux-kernel - Re: [RFC PATCH] x86/entry/64: randomize kernel stack offset upon syscall

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Message-ID: <CAGXu5jLBP-95aEF2refYimAJ=ea42C_3Ywb+1dZAaVR1rbmP9Q@mail.gmail.com>
Date:   Thu, 28 Mar 2019 09:47:56 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     Andy Lutomirski <luto@...nel.org>,
        "Reshetova, Elena" <elena.reshetova@...el.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jann Horn <jannh@...gle.com>,
        "Perla, Enrico" <enrico.perla@...el.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [RFC PATCH] x86/entry/64: randomize kernel stack offset upon syscall

On Thu, Mar 28, 2019 at 9:29 AM Andy Lutomirski <luto@...capital.net> wrote:
> Doesn’t this just leak some of the canary to user code through side channels?

Erf, yes, good point. Let's just use prandom and be done with it.

-- 
Kees Cook