[Xen-changelog] [xen master] x86: tighten page table owner checking in do_mmu_update()

[patchbot@xxxxxxx]

commit dc419f0a3752032ab00124dc55609d9231e53128
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Nov 25 10:07:09 2014 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Nov 25 10:07:09 2014 +0100

    x86: tighten page table owner checking in do_mmu_update()
    
    MMU_MACHPHYS_UPDATE, not manipulating page tables, shouldn't ignore
    a bad page table domain being specified.
    
    Also pt_owner can't be NULL when reaching the "out" label, so the
    respective check can be dropped.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Tim Deegan <tim@xxxxxxx>
    Release-Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 xen/arch/x86/mm.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 3e3353c..61b8e77 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -3618,6 +3618,11 @@ long do_mmu_update(
         break;
 
         case MMU_MACHPHYS_UPDATE:
+            if ( unlikely(d != pt_owner) )
+            {
+                rc = -EPERM;
+                break;
+            }
 
             if ( unlikely(paging_mode_translate(pg_owner)) )
             {
@@ -3693,7 +3698,7 @@ long do_mmu_update(
     perfc_add(num_page_updates, i);
 
  out:
-    if ( pt_owner && (pt_owner != d) )
+    if ( pt_owner != d )
         rcu_unlock_domain(pt_owner);
 
     /* Add incremental work we have done to the @done output parameter. */
--
generated by git-patchbot for /home/xen/git/xen.git#master

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