References: bnc#750897

---
Index: grub-1.99/grub-core/partmap/msdos.c
===================================================================
--- grub-1.99.orig/grub-core/partmap/msdos.c
+++ grub-1.99/grub-core/partmap/msdos.c
@@ -107,11 +107,15 @@ grub_partition_msdos_iterate (grub_disk_
 			(unsigned long long) p.len);
 
 	  /* If this partition is a normal one, call the hook.  */
-	  if (! grub_msdos_partition_is_empty (e->type)
-	      && ! grub_msdos_partition_is_extended (e->type))
+	  if (! grub_msdos_partition_is_empty (e->type))
 	    {
 	      p.number++;
 
+	      /* prevent someone doing mkfs or mkswap on an
+		 extended partition, but leave room for LILO */
+	      if (grub_msdos_partition_is_extended (e->type))
+	          p.len = 2;
+
 	      if (hook (disk, &p))
 		return grub_errno;
 	    }