Fix crash for badly formed ONC

chromeos/network/policy_util.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chromeos/network/policy_util.h"
 
 #include "base/logging.h"
 #include "chromeos/network/network_profile.h"
 #include "chromeos/network/network_ui_data.h"
 #include "chromeos/network/onc/onc_constants.h"
@@ skipping 29 matching lines @@
     // has no non-const iterator.
     onc_object->GetWithoutPathExpansion(field_name, &value);
     // Advance before delete.
     it.Advance();
 
     // If |value| is a dictionary, recurse.
     base::DictionaryValue* nested_object = NULL;
     if (value->GetAsDictionary(&nested_object)) {
       const onc::OncFieldSignature* field_signature =
           onc::GetFieldSignature(signature, field_name);
-
-      RemoveFakeCredentials(*field_signature->value_signature,
-                            nested_object);
+      if (field_signature)
+        RemoveFakeCredentials(*field_signature->value_signature, nested_object);
+      else
+        LOG(ERROR) << "ONC has unrecoginzed field: " << field_name;
       continue;
     }
 
     // If |value| is a string, check if it is a fake credential.
     std::string string_value;
     if (value->GetAsString(&string_value) &&
         onc::FieldIsCredential(signature, field_name)) {
       if (string_value == kFakeCredential) {
         // The value wasn't modified by the UI, thus we remove the field to keep
         // the existing value that is stored in Shill.
@@ skipping 128 matching lines @@
        it != policies.end(); ++it) {
     if (IsPolicyMatching(*it->second, actual_network))
       return it->second;
   }
   return NULL;
 }
 
 }  // namespace policy_util
 
 }  // namespace chromeos