=== modified file 'grub-core/disk/raid.c'
--- grub-core/disk/raid.c	2010-09-13 21:59:22 +0000
+++ grub-core/disk/raid.c	2010-09-25 22:20:29 +0000
@@ -501,7 +501,8 @@
           grub_dprintf ("raid", "array->nr_devs > array->total_devs (%d)?!?",
 			array->total_devs);
 
-        if (array->device[new_array->index] != NULL)
+        if ((new_array->index < GRUB_RAID_MAX_DEVICES) &&
+	    (array->device[new_array->index] != NULL))
           /* We found multiple devices with the same number. Again,
              this shouldn't happen.  */
           grub_dprintf ("raid", "Found two disks with the number %d?!?",
@@ -609,9 +610,14 @@
     }
 
   /* Add the device to the array. */
-  array->device[new_array->index] = disk;
-  array->start_sector[new_array->index] = start_sector;
-  array->nr_devs++;
+
+  /* ignore spare/faulty disks and more then GRUB_RAID_MAX_DEVICES */
+  if (new_array->index < GRUB_RAID_MAX_DEVICES)
+    {
+      array->device[new_array->index] = disk;
+      array->start_sector[new_array->index] = start_sector;
+      array->nr_devs++;
+    }
 
   return 0;
 }