[Xen-changelog] Bug fix for shadow_get_page_from_l1e(). Don't try to look for the

[BitKeeper Bot <riel@xxxxxxxxxxx>]

ChangeSet 1.1236.33.3, 2005/03/15 12:30:46+00:00, mafetter@xxxxxxxxxxxxxxxx

        Bug fix for shadow_get_page_from_l1e().  Don't try to look for the
        owner of an invalid mfn.
        
        Signed-off-by: michael.fetterman@xxxxxxxxxxxx



 arch/x86/shadow.c        |    3 ++-
 include/asm-x86/shadow.h |    6 ++++++
 2 files changed, 8 insertions(+), 1 deletion(-)


diff -Nru a/xen/arch/x86/shadow.c b/xen/arch/x86/shadow.c
--- a/xen/arch/x86/shadow.c     2005-04-05 12:08:25 -04:00
+++ b/xen/arch/x86/shadow.c     2005-04-05 12:08:25 -04:00
@@ -1724,7 +1724,8 @@
         unsigned long opte = *ppte;
         unsigned long npte = opte & ~_PAGE_RW;
 
-        shadow_get_page_from_l1e(mk_l1_pgentry(npte), d);
+        if ( npte & _PAGE_PRESENT)
+            shadow_get_page_from_l1e(mk_l1_pgentry(npte), d);
         *ppte = npte;
         put_page_from_l1e(mk_l1_pgentry(opte), d);
 
diff -Nru a/xen/include/asm-x86/shadow.h b/xen/include/asm-x86/shadow.h
--- a/xen/include/asm-x86/shadow.h      2005-04-05 12:08:24 -04:00
+++ b/xen/include/asm-x86/shadow.h      2005-04-05 12:08:25 -04:00
@@ -246,9 +246,15 @@
 shadow_get_page_from_l1e(l1_pgentry_t l1e, struct domain *d)
 {
     int res = get_page_from_l1e(l1e, d);
+    unsigned long mfn;
     struct domain *owner;
 
+    ASSERT( l1_pgentry_val(l1e) & _PAGE_PRESENT );
+
     if ( unlikely(!res) && IS_PRIV(d) && !shadow_mode_translate(d) &&
+         !(l1_pgentry_val(l1e) & L1_DISALLOW_MASK) &&
+         (mfn = l1_pgentry_to_pfn(l1e)) &&
+         pfn_is_ram(mfn) &&
          (owner = page_get_owner(pfn_to_page(l1_pgentry_to_pfn(l1e)))) &&
          (d != owner) )
     {

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