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/ByteArrayOutputStream/WriteToReleasesCarrier.java

@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2024, 2025, 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 8330748
+ * @summary Test ByteArrayOutputStream.writeTo releases carrier thread
+ * @requires vm.continuations
+ * @modules java.base/java.lang:+open
+ * @library /test/lib
+ * @run main WriteToReleasesCarrier
+ */
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.locks.LockSupport;
+import jdk.test.lib.thread.VThreadScheduler;
+
+public class WriteToReleasesCarrier {
+    public static void main(String[] args) throws Exception {
+        byte[] bytes = "Hello".getBytes(StandardCharsets.UTF_8);
+
+        var baos = new ByteArrayOutputStream();
+        baos.write(bytes);
+
+        var target = new ParkingOutputStream();
+
+        try (ExecutorService scheduler = Executors.newFixedThreadPool(1)) {
+            Thread.Builder builder = VThreadScheduler.virtualThreadBuilder(scheduler);
+            var started = new CountDownLatch(1);
+            var vthread1 = builder.start(() -> {
+                started.countDown();
+                try {
+                    baos.writeTo(target);
+                } catch (IOException ioe) { }
+            });
+            try {
+                started.await();
+                await(vthread1, Thread.State.WAITING);
+
+                // carrier should be released, use it for another thread
+                var executed = new AtomicBoolean();
+                var vthread2 = builder.start(() -> {
+                    executed.set(true);
+                });
+                vthread2.join();
+                if (!executed.get()) {
+                    throw new RuntimeException("Second virtual thread did not run");
+                }
+            } finally {
+                LockSupport.unpark(vthread1);
+                vthread1.join();
+            }
+        }
+
+        if (!Arrays.equals(target.toByteArray(), bytes)) {
+            throw new RuntimeException("Expected bytes not written");
+        }
+    }
+
+    /**
+     * Waits for a thread to get to the expected state.
+     */
+    private static void await(Thread thread, Thread.State expectedState) throws Exception {
+        Thread.State state = thread.getState();
+        while (state != expectedState) {
+            Thread.sleep(10);
+            state = thread.getState();
+        }
+    }
+
+    /**
+     * An OutputStream that parks when writing.
+     */
+    static class ParkingOutputStream extends OutputStream {
+        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+
+        @Override
+        public void write(int i) {
+            LockSupport.park();
+            baos.write(i);
+        }
+
+        @Override
+        public void write(byte[] b, int off, int len) {
+            LockSupport.park();
+            baos.write(b, off, len);
+        }
+
+        byte[] toByteArray() {
+            return baos.toByteArray();
+        }
+    }
+}