diff -r 660cd5afaa97 xen/drivers/passthrough/vtd/dmar.c
--- a/xen/drivers/passthrough/vtd/dmar.c	Tue Jul 22 21:12:44 2008 +0800
+++ b/xen/drivers/passthrough/vtd/dmar.c	Wed Jul 23 16:05:55 2008 +0800
@@ -349,6 +349,12 @@ acpi_parse_one_rmrr(struct acpi_dmar_ent
     void *dev_scope_start, *dev_scope_end;
     int ret = 0;
 
+    if ( rmrr->base_address >= rmrr->end_address )
+    {
+        dprintk(XENLOG_ERR VTDPREFIX, "RMRR is incorrect.\n");
+        return -EFAULT;
+    }
+
     rmrru = xmalloc(struct acpi_rmrr_unit);
     if ( !rmrru )
         return -ENOMEM;