On Tue, Oct 05, 2021 at 10:43:13PM +0100, Matthew Wilcox wrote:
> 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?
Ah yeah, that'd be good!
-Kees
>
> > 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
--
Kees Cook
