On Tue, Oct 05, 2021 at 02:23:09PM -0700, Kees Cook wrote:
> > + if (is_kmap_addr(ptr)) {
> > + unsigned long page_end = (unsigned long)ptr | (PAGE_SIZE - 1);
> > +
> > + if ((unsigned long)ptr + n - 1 > page_end)
> > + usercopy_abort("kmap", NULL, to_user, 0, n);
>
> It's likely not worth getting an offset here, but "0" above could be
> something like "ptr - PKMAP_ADDR(0)".
Mmm. page_offset(ptr) should do the trick, no?
> Either way:
>
> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
>
> Thanks!
>
> -Kees
>
> > + return;
> > + }
> > +
> > + page = virt_to_head_page(ptr);
> >
> > if (PageSlab(page)) {
> > /* Check slab allocator for flags and size. */
> > --
> > 2.32.0
> >
>
> --
> Kees Cook
