Re: [PATCH] x86/mm: Remove set_pages_x() and set_pages_nx()

[Larry Finger]

On 9/18/19 11:45 AM, Christoph Hellwig wrote:
> On Wed, Sep 18, 2019 at 11:41:21AM -0500, Larry Finger wrote:
> > In commit 185be15143aa ("x86/mm: Remove set_pages_x() and set_pages_nx()"),
> > the wrappers were removed as they did not provide a real benefit over
> > set_memory_x() and set_memory_nx(). This change causes a problem because
> > the wrappers were exported, but the underlying routines were not. As a
> > result, external modules that used the wrappers would need to recreate
> > a significant part of memory management.
>
> And external modules do not matter for mainline decisions.  In fact
> ensuring random modules can't mess with the NX state was one of the
> reasons for this patch, as that is a security issue waiting to happen.

Christoph,

Is there approved way for pages to be set to be executable by an external module 
that would not be a security issue?

Larry