File 546b4669-x86-don-t-allow-page-table-updates-on-non-PV-pts.patch of Package xen.481

References: bsc#903967 CVE-2014-8594 XSA-109

# Commit e4292c5aac41b80f33d4877104348d5ee7c95aa4
# Date 2014-11-18 14:15:21 +0100
# Author Jan Beulich <jbeulich@suse.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86: don't allow page table updates on non-PV page tables in do_mmu_update()

paging_write_guest_entry() and paging_cmpxchg_guest_entry() aren't
consistently supported for non-PV guests (they'd deref NULL for PVH or
non-HAP HVM ones). Don't allow respective MMU_* operations on the
page tables of such domains.

This is CVE-2014-8594 / XSA-109.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Tim Deegan <tim@xen.org>

--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -3509,6 +3509,10 @@ long do_mmu_update(
         {
             p2m_type_t p2mt;
 
+            rc = -EOPNOTSUPP;
+            if ( unlikely(paging_mode_refcounts(pt_owner)) )
+                break;
+
             xsm_needed |= XSM_MMU_NORMAL_UPDATE;
             if ( get_pte_flags(req.val) & _PAGE_PRESENT )
             {