2 files changed, 52 insertions, 0 deletions
diff --git a/phpBB/phpbb/auth/provider/oauth/oauth.php b/phpBB/phpbb/auth/provider/oauth/oauth.php
index 1a3083d42e..0d94acfbca 100644
--- a/phpBB/phpbb/auth/provider/oauth/oauth.php
+++ b/phpBB/phpbb/auth/provider/oauth/oauth.php
@@ -634,6 +634,21 @@ class oauth extends \phpbb\auth\provider\base
 	*/
 	protected function link_account_perform_link(array $data)
 	{
+		// Check if the external account is already associated with other user
+		$sql = 'SELECT user_id
+			FROM ' . $this->auth_provider_oauth_token_account_assoc . "
+			WHERE provider = '" . $this->db->sql_escape($data['provider']) . "'
+				AND oauth_provider_id = '" . $this->db->sql_escape($data['oauth_provider_id']) . "'";
+		$result = $this->db->sql_query($sql);
+		$row = $this->db->sql_fetchrow($result);
+		$this->db->sql_freeresult($result);
+
+		if ($row)
+		{
+			trigger_error('AUTH_PROVIDER_OAUTH_ERROR_ALREADY_LINKED');
+		}
+
+		// Link account
 		$sql = 'INSERT INTO ' . $this->auth_provider_oauth_token_account_assoc . '
 			' . $this->db->sql_build_array('INSERT', $data);
 		$this->db->sql_query($sql);
diff --git a/phpBB/phpbb/db/migration/data/v32x/v328rc1.php b/phpBB/phpbb/db/migration/data/v32x/v328rc1.php
new file mode 100644
index 0000000000..fa43cf33a7
--- /dev/null
+++ b/phpBB/phpbb/db/migration/data/v32x/v328rc1.php
@@ -0,0 +1,37 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+namespace phpbb\db\migration\data\v32x;
+
+class v328rc1 extends \phpbb\db\migration\migration
+{
+	public function effectively_installed()
+	{
+		return phpbb_version_compare($this->config['version'], '3.2.8-RC1', '>=');
+	}
+
+	static public function depends_on()
+	{
+		return array(
+			'\phpbb\db\migration\data\v32x\timezone_p3',
+			'\phpbb\db\migration\data\v32x\v327',
+		);
+	}
+
+	public function update_data()
+	{
+		return array(
+			array('config.update', array('version', '3.2.8-RC1')),
+		);
+	}
+}