Only check the well-known password if we know it is not owned.

tpm.cc

 // Copyright (c) 2009-2010 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.
 
 // Contains the implementation of class Tpm
 
 #include "tpm.h"
 
 #include <base/file_util.h>
 #include <base/platform_thread.h>
@@ skipping 550 matching lines @@
                                            SRK_UUID, &srk_handle))) {
     is_srk_available_ = false;
   } else {
     Tspi_Context_CloseObject(context_handle_, srk_handle);
     is_srk_available_ = true;
   }
 
   // If we can open the TPM with the default password, then we still need to
   // zero the SRK password and unrestrict it, then change the owner password.
   TSS_HTPM tpm_handle;
-  if (GetTpmWithAuth(context_handle_, default_owner_password, &tpm_handle) &&
+  if (!file_util::PathExists(FilePath(kTpmOwnedFile)) &&
+      GetTpmWithAuth(context_handle_, default_owner_password, &tpm_handle) &&
       TestTpmAuth(tpm_handle)) {
     if (!ZeroSrkPassword(context_handle_, default_owner_password)) {
       LOG(ERROR) << "Couldn't zero SRK password";
       is_being_owned_ = false;
       return false;
     }
 
     if (!UnrestrictSrk(context_handle_, default_owner_password)) {
       LOG(ERROR) << "Couldn't unrestrict the SRK";
       is_being_owned_ = false;
@@ skipping 45 matching lines @@
   }
   memcpy(random.data(), tpm_data, random.size());
   Tspi_Context_FreeMemory(context_handle, tpm_data);
   chromeos::SecureMemset(tpm_data, 0, random.size());
   Tspi_Context_Close(context_handle);
   data->swap(random);
   return true;
 }
 
 } // namespace tpm_init