undefect. CWE-407 — 63 sites patched across 27 ecosystems

Authors: russell@unturf.com · brackishbert@gmail.com · foxhop.net · TimeHexOn.com

Patches, unit tests, benchmarks, whitepaper, and outreach briefs.
Public domain — no copyright claimed. Use freely.

test/jdk/java/io/PrintStream/OversynchronizedTest.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/* @test
+   @bug 4905777
+   @summary PrintStream.println(Object) oversynchronized, can deadlock
+   @key randomness
+*/
+
+import java.io.PrintStream;
+
+public class OversynchronizedTest extends Thread {
+    private static TestObj testObj = new TestObj("This is a test.");
+    private static int loopNum = 100;
+
+    public void run() {
+        for(int i=0; i<loopNum; i++) {
+            testObj.test();
+
+            //passing an object to System.out.println might cause deadlock
+            //if the object has a synchronized toString() method.
+            //using System.out.println(testObj.toString()) won't have a problem
+           System.out.println(testObj);
+        }
+    }
+
+    public static void main(String args[]) throws Exception {
+        // should no NullPointerException
+        System.out.println((Object)null);
+
+        // over synch test
+        int num = 5;
+
+        OversynchronizedTest[] t = new OversynchronizedTest[num];
+        for(int i=0; i<num; i++) {
+            t[i] = new OversynchronizedTest();
+            t[i].start();
+        }
+
+        for(int i=0; i <num; i++) {
+            t[i].join();
+        }
+
+        System.out.println("Test completed.");
+    }
+}
+
+class TestObj {
+    String mStr;
+
+    TestObj(String str) {
+        mStr = str;
+    }
+
+    synchronized void test() {
+        try {
+            long t = Math.round(Math.random()*10);
+            Thread.currentThread().sleep(t);
+        } catch (InterruptedException e) {
+            // jtreg timeout?
+            // Only jtreg will interrupt this thread so it knows what to do:
+            e.printStackTrace();
+        }
+
+        //the following line might cause hang if there is System.out.println(testObj)
+        //called by other threads.
+        System.out.println("In test().");
+    }
+
+    public synchronized String toString() {
+        System.out.println("Calling toString\n");
+        return mStr;
+    }
+}