On Wed, 29 Aug 2018, Nadav Amit wrote:
> at 8:47 AM, Andy Lutomirski <l...@kernel.org> wrote:
>
> > In NMI context, we might be in the middle of context switching or in
> > the middle of switch_mm_irqs_off(). In either case, CR3 might not
> > match current->mm, which could cause copy_from_user_nmi() and
> > friends to read the wrong memory.
> >
> > Fix it by adding a new nmi_uaccess_okay() helper and checking it in
> > copy_from_user_nmi() and in __copy_from_user_nmi()'s callers.
> >
> > Cc: sta...@vger.kernel.org
> > Cc: Peter Zijlstra <pet...@infradead.org>
> > Cc: Nadav Amit <nadav.a...@gmail.com>
> > Signed-off-by: Andy Lutomirski <l...@kernel.org>
> > ---
> >
> > Nadav, this is intended for your series. Want to add it right
> > before the use_temporary_mm() stuff?
>
> Sure. Thanks! I will apply the following small fix:
>
> > +
> > +#ifdef CONFIG_DEBUG_VM
> > + WARN_ON_ONCE(!loaded_mm);
> > +#endif
>
> Will be changed to VM_WARN_ON_ONCE() in the two instances.
Unless I'm completely lost, this can just be applied to tip right
away. It's not depending on anything else.
Thanks,
tglx
