On Mon, Jun 13, 2022 at 09:23:15AM -0700, Kees Cook wrote:
> On Sun, Jun 12, 2022 at 10:32:25PM +0100, Matthew Wilcox (Oracle) wrote:
> > vmalloc does not allocate a vm_struct for vm_map_ram() areas. That causes
> > us to deny usercopies from those areas. This affects XFS which uses
> > vm_map_ram() for its directories.
> >
> > Fix this by calling find_vmap_area() instead of find_vm_area().
>
> Thanks for the fixes!
>
> > [...]
> > + /* XXX: We should also abort for free vmap_areas */
>
> What's needed to detect this?
I'm not entirely sure. I only just learned of the existence of this
struct ;-)
/*
* The following two variables can be packed, because
* a vmap_area object can be either:
* 1) in "free" tree (root is free_vmap_area_root)
* 2) or "busy" tree (root is vmap_area_root)
*/
union {
unsigned long subtree_max_size; /* in "free" tree */
struct vm_struct *vm; /* in "busy" tree */
};
Hmm. Actually, we only search vmap_area_root, so I suppose it can't
be a free area. So this XXX can be removed, as we'll get NULL back
if we've got a pointer to a free area. Ulad, do I have this right?
