Re: [PATCH 5/5] x86/traps: avoid KMSAN bugs originating from handle_bug()

[Alexander Potapenko]

On Thu, Nov 3, 2022 at 12:18 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Wed, Nov 02, 2022 at 12:06:11PM +0100, Alexander Potapenko wrote:
>
> > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> > index 178015a820f08..d3fdec706f1d2 100644
> > --- a/arch/x86/kernel/traps.c
> > +++ b/arch/x86/kernel/traps.c
> > @@ -15,6 +15,7 @@
> >  #include <linux/context_tracking.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/kallsyms.h>
> > +#include <linux/kmsan.h>
> >  #include <linux/spinlock.h>
> >  #include <linux/kprobes.h>
> >  #include <linux/uaccess.h>
> > @@ -301,6 +302,12 @@ static noinstr bool handle_bug(struct pt_regs *regs)
> >  {
> >       bool handled = false;
> >
> > +     /*
> > +      * Normally @regs are unpoisoned by irqentry_enter(), but handle_bug()
> > +      * is a rare case that uses @regs without passing them to
> > +      * irqentry_enter().
> > +      */
> > +     kmsan_unpoison_entry_regs(regs);
> >       if (!is_valid_bugaddr(regs->ip))
> >               return handled;
> >
>
> Should we place this kmsan_unpoison_entry_regs() after the
> instrumentation_begin() ?

Agreed, let me send an update.

-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

Geschäftsführer: Paul Manicle, Liana Sebastian
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg