Re: [PATCH v3] powerpc: Do not make the entire heap executable

[Denys Vlasenko]

On 08/10/2016 12:43 AM, Kees Cook wrote:
> > -static int do_brk(unsigned long addr, unsigned long len)
> > +static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags)
> >  {
> >         struct mm_struct *mm = current->mm;
> >         struct vm_area_struct *vma, *prev;
> > -       unsigned long flags;
> >         struct rb_node **rb_link, *rb_parent;
> >         pgoff_t pgoff = addr >> PAGE_SHIFT;
> >         int error;
> > @@ -2666,7 +2665,7 @@ static int do_brk(unsigned long addr, unsigned long len)
> >         if (!len)
> >                 return 0;
> >
> > -       flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
> > +       flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
>
> For sanity's sake, should a mask be applied here? i.e. to be extra
> careful about what flags can get passed in?

Maybe... I am leaving it to mm experts.

> Otherwise, this looks okay to me:
>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
>
> -Kees