[Xen-changelog] [xen stable-4.2] x86: don't allow page table updates on non-PV page tables in do_mmu_update()

[patchbot@xxxxxxx]

commit 6791ab169fe6b2cd7c69a5140cd229d036e706b0
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Nov 18 14:32:57 2014 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Nov 18 14:32:57 2014 +0100

    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@xxxxxxxx>
    Acked-by: Tim Deegan <tim@xxxxxxx>
---
 xen/arch/x86/mm.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 9ec617b..121aef4 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -3794,6 +3794,10 @@ long do_mmu_update(
         {
             p2m_type_t p2mt;
 
+            rc = -EOPNOTSUPP;
+            if ( unlikely(paging_mode_refcounts(pt_owner)) )
+                break;
+
             rc = xsm_mmu_normal_update(d, pt_owner, pg_owner, req.val);
             if ( rc )
                 break;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog