Only advance kernel version when the booted partition has a valid key block

firmware/lib/tpm_lite/tlcl.c

-/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+/* Copyright (c) 2010-2011 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /* A lightweight TPM command library.
  *
  * The general idea is that TPM commands are array of bytes whose
  * fields are mostly compile-time constant.  The goal is to build much
  * of the commands at compile time (or build time) and change some of
  * the fields at run time as needed.  The code in
@@ skipping 306 matching lines @@
   Memcpy(&cmd, &tpm_getpermissions_cmd, sizeof(cmd));
   ToTpmUint32(cmd.buffer + tpm_getpermissions_cmd.index, index);
   result = TlclSendReceive(cmd.buffer, response, sizeof(response));
   if (result != TPM_SUCCESS)
     return result;
 
   nvdata = response + kTpmResponseHeaderLength + sizeof(size);
   FromTpmUint32(nvdata + kNvDataPublicPermissionsOffset, permissions);
   return result;
 }