From 5be4e8cb1b01ef80ba464de9b108ba0983078cad Mon Sep 17 00:00:00 2001
From: Alexander Soklakov <alexander.soklakov@oracle.com>
Date: Wed, 17 Feb 2021 14:53:31 +0400
Subject: [PATCH] Fix for Bug#22508715, SETSESSIONMAXROWS() CALL ON CLOSED
 CONNECTION RESULTS IN NPE.

---
 CHANGES                                         |  2 ++
 .../java/com/mysql/cj/jdbc/ConnectionImpl.java  |  3 ++-
 .../regression/ConnectionRegressionTest.java    | 17 +++++++++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/CHANGES b/CHANGES
index 72372da30..596e22873 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3,6 +3,8 @@
 
 Version 8.0.24
 
+  - Fix for Bug#22508715, SETSESSIONMAXROWS() CALL ON CLOSED CONNECTION RESULTS IN NPE.
+
   - Fix for Bug#102131 (32338451), UPDATABLERESULTSET NPE WHEN USING DERIVED QUERIES OR VIEWS.
 
   - Fix for Bug#101596 (32151143), GET THE 'HOST' PROPERTY ERROR AFTER CALLING TRANSFORMPROPERTIES() METHOD.
diff --git a/src/main/user-impl/java/com/mysql/cj/jdbc/ConnectionImpl.java b/src/main/user-impl/java/com/mysql/cj/jdbc/ConnectionImpl.java
index 6d5b6cb46..b8aa34781 100644
--- a/src/main/user-impl/java/com/mysql/cj/jdbc/ConnectionImpl.java
+++ b/src/main/user-impl/java/com/mysql/cj/jdbc/ConnectionImpl.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2020, Oracle and/or its affiliates.
+ * Copyright (c) 2002, 2021, Oracle and/or its affiliates.
  *
  * This program is free software; you can redistribute it and/or modify it under
  * the terms of the GNU General Public License, version 2.0, as published by the
@@ -2426,6 +2426,7 @@ public int getSessionMaxRows() {
     @Override
     public void setSessionMaxRows(int max) throws SQLException {
         synchronized (getConnectionMutex()) {
+            checkClosed();
             if (this.session.getSessionMaxRows() != max) {
                 this.session.setSessionMaxRows(max);
                 this.session.execSQL(null, "SET SQL_SELECT_LIMIT=" + (this.session.getSessionMaxRows() == -1 ? "DEFAULT" : this.session.getSessionMaxRows()),
diff --git a/src/test/java/testsuite/regression/ConnectionRegressionTest.java b/src/test/java/testsuite/regression/ConnectionRegressionTest.java
index a82eaaa5f..e584ee662 100644
--- a/src/test/java/testsuite/regression/ConnectionRegressionTest.java
+++ b/src/test/java/testsuite/regression/ConnectionRegressionTest.java
@@ -11796,4 +11796,21 @@ public Properties transformProperties(Properties props) {
             return props;
         }
     }
+
+    /**
+     * Tests fix for Bug#22508715, SETSESSIONMAXROWS() CALL ON CLOSED CONNECTION RESULTS IN NPE.
+     * 
+     * @throws Exception
+     */
+    @Test
+    public void testBug22508715() throws Exception {
+        Properties props = new Properties();
+        Connection con = getConnectionWithProps(props);
+        con.close();
+
+        assertThrows(SQLNonTransientConnectionException.class, "No operations allowed after connection closed.*", () -> {
+            ((JdbcConnection) con).setSessionMaxRows(0);
+            return null;
+        });
+    }
 }