Re: [PATCH v2] futex: Use-after-free between futex_key_to_node_opt and vma_replace_policy

[Hao-Yu Yang]

I need to send patch v3? If i need how i need to change about this patch?

On Wed, Mar 25, 2026 at 08:25:29AM -0700, Eric Dumazet wrote:
> On Wed, Mar 25, 2026 at 8:22 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> 
> > Fair enough. Like so then..
> >
> > --- a/kernel/futex/core.c
> > +++ b/kernel/futex/core.c
> > @@ -342,7 +342,7 @@ static int __futex_key_to_node(struct mm
> >         if (!vma)
> >                 return FUTEX_NO_NODE;
> >
> > -       mpol = vma_policy(vma);
> > +       mpol = READ_ONCE(vma->vm_policy);
> >         if (!mpol)
> >                 return FUTEX_NO_NODE;
> >
> > --- a/mm/mempolicy.c
> > +++ b/mm/mempolicy.c
> > @@ -1026,7 +1026,7 @@ static int vma_replace_policy(struct vm_
> >         }
> >
> >         old = vma->vm_policy;
> > -       vma->vm_policy = new; /* protected by mmap_lock */
> > +       WRITE_ONCE(vma->vm_policy, new); /* protected by mmap_lock */
> >         mpol_put(old);
> >
> >         return 0;
> 
> LGTM, thanks !
> 
> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>