diff -r 9dd91e9691a2 xen/include/xsm/xsm.h
--- a/xen/include/xsm/xsm.h	Sat Apr 02 15:58:54 2011 +0100
+++ b/xen/include/xsm/xsm.h	Mon Apr 04 09:19:26 2011 -0400
@@ -427,7 +427,11 @@
 
 static inline long __do_xsm_op (XEN_GUEST_HANDLE(xsm_op_t) op)
 {
-    return xsm_call(__do_xsm_op(op));
+#ifdef XSM_ENABLE
+    return xsm_ops->__do_xsm_op(op);
+#else
+    return -ENOSYS;
+#endif
 }
 
 #ifdef XSM_ENABLE
diff -r 9dd91e9691a2 xen/xsm/flask/flask_op.c
--- a/xen/xsm/flask/flask_op.c	Sat Apr 02 15:58:54 2011 +0100
+++ b/xen/xsm/flask/flask_op.c	Mon Apr 04 09:19:26 2011 -0400
@@ -485,6 +485,9 @@
     if ( length < 0 )
         goto out;
 
+    if (len > count)
+        return -ERANGE; 
+
     memset(buf, 0, count);
     memcpy(buf, context, len);
     length = len;