Check username validity in the FakeAuthPolicyClient

chromeos/dbus/fake_auth_policy_client.cc

Index: chromeos/dbus/fake_auth_policy_client.cc
diff --git a/chromeos/dbus/fake_auth_policy_client.cc b/chromeos/dbus/fake_auth_policy_client.cc
index f37f1ea53bc88d6aa576485db9d67fb310e6978b..78f3edcf4cef525e55ee06aa34be27f2e3c1f8b0 100644
--- a/chromeos/dbus/fake_auth_policy_client.cc
+++ b/chromeos/dbus/fake_auth_policy_client.cc
@@ -10,6 +10,7 @@
 #include "base/location.h"
 #include "base/md5.h"
 #include "base/path_service.h"
+#include "base/strings/string_split.h"
 #include "base/task_scheduler/post_task.h"
 #include "chrome/browser/chromeos/policy/proto/chrome_device_policy.pb.h"
 #include "chromeos/chromeos_paths.h"
@@ -65,6 +66,13 @@ void FakeAuthPolicyClient::JoinAdDomain(const std::string& machine_name,
                                         const std::string& user_principal_name,
                                         int password_fd,
                                         const JoinCallback& callback) {
+  std::vector<std::string> parts = base::SplitString(
+      user_principal_name, "@", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
+  if (parts.size() != 2U) {

[Thiemo Nagel, 2017/01/24 14:17:36]

It seems that you'll have to check the sizes of the parts as well.  I still
managed to crash Chrome by entering "a@ " as the user name.

Nit: Imho "2U" is uncommon, "2" would be easier to read.

[achuithb, 2017/01/24 19:42:11]

Sounds like we need a unit test

[Roman Sorokin (ftl), 2017/01/25 11:50:18]

Done.

[Roman Sorokin (ftl), 2017/01/25 11:50:18]

Done.

+    callback.Run(authpolicy::ERROR_PARSE_UPN_FAILED);
+    return;
+  }
+
   callback.Run(authpolicy::ERROR_NONE);
 }