linux-kernel - Re: Avoid speculative indirect calls in kernel

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Message-ID: <20180105120647.0c717720@alans-desktop>
Date:   Fri, 5 Jan 2018 12:06:47 +0000
From:   Alan Cox <gnomes@...rguk.ukuu.org.uk>
To:     james harvey <jamespharvey20@...il.com>
Cc:     Jiri Kosina <jikos@...nel.org>, Andi Kleen <andi@...stfloor.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...ux-foundation.org>,
        dwmw@...zon.co.uk, Tim Chen <tim.c.chen@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Dave Hansen <dave.hansen@...el.com>
Subject: Re: Avoid speculative indirect calls in kernel

> But, are the GCC patches being discussed also expected to fix the
> vulnerability because user binaries will be compiled using them?  In

If you have a system with just a few user binaries where you are
concerned about such a thing you might go that way.

> such case, a binary could be maliciously changed back, or a custom GCC
> made with the patches reverted.

If I can change your gcc or your binary then instead of removing the
speculation protection I can make it encrypt all your files instead. Much
simpler.

At the point I can do this you already lost.

Alan