[Xen-changelog] [xen-3.4-testing] x86: add an extra check when validating a huge pv L2 entry

["Xen patchbot-3.4-testing" <patchbot-3.4-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1254409538 -3600
# Node ID e34a589a1bc896fb9582a1387f99cda5a1624807
# Parent  c3767592b4a84987f9b0df87b554262ea9d00845
x86: add an extra check when validating a huge pv L2 entry

While get_page_and_type_from_pagenr() (through get_page_from_pagenr())
does the needed mfn_valid() check, get_data_page() doesn't and, it
being passed a struct page_info pointer, really expects it's caller(s)
to do.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
xen-unstable changeset:   20189:d2a32e24fe50
xen-unstable date:        Wed Sep 09 16:39:41 2009 +0100
---
 xen/arch/x86/mm.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff -r c3767592b4a8 -r e34a589a1bc8 xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c Thu Oct 01 16:00:10 2009 +0100
+++ b/xen/arch/x86/mm.c Thu Oct 01 16:05:38 2009 +0100
@@ -844,14 +844,16 @@ get_page_from_l2e(
         int writeable = !!(l2e_get_flags(l2e) & _PAGE_RW);
   
         do {
-            rc = get_data_page(mfn_to_page(m), d, writeable);
-            if ( unlikely(!rc) )
+            if ( !mfn_valid(m) ||
+                 !get_data_page(mfn_to_page(m), d, writeable) )
             {
                 while ( m-- > mfn )
                     put_data_page(mfn_to_page(m), writeable);
                 return -EINVAL;
             }
         } while ( m++ < (mfn + (L1_PAGETABLE_ENTRIES-1)) );
+
+        rc = 1;
 
 #ifdef __x86_64__
         map_pages_to_xen(

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