linux-kernel - Re: [tip:x86/pti] module: Add retpoline tag to VERMAGIC

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Date:   Thu, 18 Jan 2018 18:39:50 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
cc:     tip-bot for Andi Kleen <tipbot@...or.com>,
        linux-tip-commits@...r.kernel.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, ak@...ux.intel.com, dwmw@...zon.co.uk,
        mingo@...nel.org, hpa@...or.com
Subject: Re: [tip:x86/pti] module: Add retpoline tag to VERMAGIC

On Thu, 18 Jan 2018, Josh Poimboeuf wrote:

> On Wed, Jan 17, 2018 at 02:40:43AM -0800, tip-bot for Andi Kleen wrote:
> > Commit-ID:  6cfb521ac0d5b97470883ff9b7facae264b7ab12
> > Gitweb:     https://git.kernel.org/tip/6cfb521ac0d5b97470883ff9b7facae264b7ab12
> > Author:     Andi Kleen <ak@...ux.intel.com>
> > AuthorDate: Tue, 16 Jan 2018 12:52:28 -0800
> > Committer:  Thomas Gleixner <tglx@...utronix.de>
> > CommitDate: Wed, 17 Jan 2018 11:35:14 +0100
> > 
> > module: Add retpoline tag to VERMAGIC
> > 
> > Add a marker for retpoline to the module VERMAGIC. This catches the case
> > when a non RETPOLINE compiled module gets loaded into a retpoline kernel,
> > making it insecure.
> > 
> > It doesn't handle the case when retpoline has been runtime disabled.  Even
> > in this case the match of the retcompile status will be enforced.  This
> > implies that even with retpoline run time disabled all modules loaded need
> > to be recompiled.
> 
> If the user overrides the vermagic and loads the module, shouldn't we
> update the spectre_v2 sysfs vulnerability status and print a warning
> like in v2?

If the user does that then the sysfs output is not our problem anymore,
really.

Thanks,

	tglx