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/hotspot/jtreg/runtime/ParallelLoad/ParallelSuper/MyLoader.java

@@ -0,0 +1,156 @@
+/*
+ * Copyright (c) 2021, 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.
+ */
+
+import java.io.*;
+import jdk.test.lib.classloader.ClassUnloadCommon;
+import java.util.concurrent.Semaphore;
+
+// This class loader will deadlock where one thread has a lock for A, trying to get a lock for B
+// and the other thread has a lock for B, trying to get a lock for A in the case of
+// A extends B extends A.  It should throw ClassCircularityError from both threads.
+
+class MyLoader extends ClassLoader {
+    static {
+        registerAsParallelCapable();
+    }
+
+    private static boolean first = true;
+
+    public Class loadClass(String name) throws ClassNotFoundException {
+        // Wait before getting B lock.
+        if (name.equals("B") && first) {
+            first = false;
+            makeThreadWait();
+        }
+        synchronized(getClassLoadingLock(name)) {
+            Class<?> c = findLoadedClass(name);
+            if (c != null) return c;
+
+            if (name.equals("B") && !first) {
+              wakeUpThread();
+            }
+
+            byte[] b = loadClassData(name);
+            if (b != null) {
+                return defineClass(name, b, 0, b.length);
+            } else {
+                return super.loadClass(name);
+            }
+        }
+    }
+
+    private static boolean parallel = false;
+    private Object sync = new Object();
+    private static volatile boolean waiting = false;
+    private static Semaphore mainSem = new Semaphore(0);
+
+    private void makeThreadWait() {
+        if (!parallel) { return; }
+
+        // Signal main thread to start t2.
+        mainSem.release();
+
+        if (isRegisteredAsParallelCapable()) {
+            synchronized(sync) {
+                try {
+                    ThreadPrint.println("t1 waits parallelCapable loader");
+                    waiting = true;
+                    sync.wait();  // Give up lock before request to load B
+                } catch (InterruptedException e) {}
+             }
+         } else {
+             try {
+                ThreadPrint.println("t1 waits non-parallelCapable loader");
+                wait(200);  // Give up lock before request to load B
+              } catch (InterruptedException e) {}
+         }
+    }
+
+    // Parallel capable loader should wake up the first thread.
+    // Non-parallelCapable class loader thread will be woken up by the jvm.
+    private void wakeUpThread() {
+        if (isRegisteredAsParallelCapable()) {
+            while (!waiting) {
+                try {
+                    Thread.sleep(1);
+                } catch (InterruptedException e) {}
+            }
+            synchronized(sync) {
+                sync.notify();
+            }
+        }
+    }
+
+    private byte[] loadClassData(String name) {
+        if (name.equals("A")) {
+            ThreadPrint.println("loading A extends B");
+            return ClassUnloadCommon.getClassData("A");
+        } else if (name.equals("B")) {
+            ThreadPrint.println("loading B extends A");
+            try {
+                return AsmClasses.dumpB();
+            } catch (Exception e) {
+                e.printStackTrace();
+                return null;
+            }
+        } else if (!name.startsWith("java")) {
+            return ClassUnloadCommon.getClassData(name);
+        }
+        return null;
+    }
+
+
+    ClassLoadingThread[] threads = new ClassLoadingThread[2];
+    private boolean success = true;
+
+    public boolean report_success() {
+        for (int i = 0; i < 2; i++) {
+          try {
+            threads[i].join();
+            if (!threads[i].report_success()) success = false;
+          } catch (InterruptedException e) {}
+        }
+        return success;
+    }
+
+    void startLoading() {
+
+        for (int i = 0; i < 2; i++) {
+            threads[i] = new ClassLoadingThread(this, parallel ? null : mainSem);
+            threads[i].setName("Loading Thread #" + (i + 1));
+            threads[i].start();
+            System.out.println("Thread " + (i + 1) + " was started...");
+            // wait to start the second thread if not concurrent
+            if (i == 0) {
+                try {
+                    ThreadPrint.println("Main thread calls mainSem.acquire()");
+                    mainSem.acquire();
+                } catch (InterruptedException e) {}
+            }
+        }
+    }
+
+    MyLoader(boolean load_in_parallel) {
+       parallel = load_in_parallel;
+    }
+}