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Date:   Thu, 26 Jul 2018 12:37:19 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     salyzyn@android.com, LKML <linux-kernel@vger.kernel.org>,
        mingo@redhat.com, kernel-team@android.com, stable@vger.kernel.org
Subject: Re: [PATCH] tracing: do not leak kernel addresses
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On Thu, 26 Jul 2018 09:32:07 -0700
Nick Desaulniers <ndesaulniers@google.com> wrote:

> On Thu, Jul 26, 2018 at 8:22 AM Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > On Thu, 26 Jul 2018 08:14:08 -0700
> > Mark Salyzyn <salyzyn@android.com> wrote:
> >  
> > > Thank you Steve, much appreciated feedback, I have asked the security
> > > developers to keep this in mind and come up with a correct fix.
> > >
> > > The correct fix that meets your guidelines would _not_ be suitable for
> > > stable due to the invasiveness it sounds, only for the latest will such
> > > a rework make sense. As such, the fix proposed in this patch is the only
> > > one that meets the bar for stable patch simplicity, and merely(!) needs
> > > to state that if the fix is taken, perf and trace are broken.
> > >
> > > Posting this patch publicly on the lists, that may never be applied, may
> > > be the limit of our responsibility for a fix to stable kernel releases,
> > > to be optionally applied by vendors concerned with this CVE criteria?
> > >  
> >
> > The patch breaks the code it touches. It makes it useless.  
> 
> Doesn't that depend on kptr_restrict, or would it be broken if
> kptr_restrict was set to 0?

Is that what governs the output of kallsyms?

-- Steve