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/lang/Thread/virtual/stress/GetStackTraceALotWhenPinned.java

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+/*
+ * Copyright (c) 2023, 2026, 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 8322818
+ * @summary Stress test Thread.getStackTrace on a virtual thread that is pinned
+ * @requires vm.debug != true
+ * @modules jdk.management
+ * @library /test/lib
+ * @run main/othervm/native/timeout=300 --enable-native-access=ALL-UNNAMED GetStackTraceALotWhenPinned 10000
+ */
+
+/*
+ * @test
+ * @requires vm.debug == true
+ * @modules jdk.management
+ * @library /test/lib
+ * @run main/othervm/native/timeout=300 --enable-native-access=ALL-UNNAMED GetStackTraceALotWhenPinned 5000
+ */
+
+import java.time.Instant;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.LockSupport;
+import jdk.test.lib.Platform;
+import jdk.test.lib.thread.VThreadRunner;   // ensureParallelism requires jdk.management
+import jdk.test.lib.thread.VThreadPinner;
+
+public class GetStackTraceALotWhenPinned {
+
+    public static void main(String[] args) throws Exception {
+        // need at least two carrier threads when main thread is a virtual thread
+        if (Thread.currentThread().isVirtual()) {
+            VThreadRunner.ensureParallelism(2);
+        }
+
+        int iterations;
+        int value = Integer.parseInt(args[0]);
+        if (Platform.isOSX()) {
+            // reduced iterations on macosx
+            iterations = Math.max(value / 4, 1);
+        } else {
+            iterations = value;
+        }
+
+        var barrier = new Barrier(2);
+
+        // Start a virtual thread that loops doing Thread.yield and parking while pinned.
+        // This loop creates the conditions for the main thread to sample the stack trace
+        // as it transitions from being unmounted to parking while pinned.
+        var thread = Thread.startVirtualThread(() -> {
+            boolean timed = false;
+            for (int i = 0; i < iterations; i++) {
+                // wait for main thread to arrive
+                barrier.await();
+
+                Thread.yield();
+                boolean b = timed;
+                VThreadPinner.runPinned(() -> {
+                    if (b) {
+                        LockSupport.parkNanos(Long.MAX_VALUE);
+                    } else {
+                        LockSupport.park();
+                    }
+                });
+                timed = !timed;
+            }
+        });
+
+        long lastTime = System.nanoTime();
+        for (int i = 1; i <= iterations; i++) {
+            // wait for virtual thread to arrive
+            barrier.await();
+
+            thread.getStackTrace();
+            LockSupport.unpark(thread);
+
+            long currentTime = System.nanoTime();
+            if (i == iterations || ((currentTime - lastTime) > 1_000_000_000L)) {
+                System.out.format("%s => %d of %d%n", Instant.now(), i, iterations);
+                lastTime = currentTime;
+            }
+
+            if (Thread.currentThread().isInterrupted()) {
+                // fail quickly if interrupted by jtreg
+                throw new RuntimeException("interrupted");
+            }
+        }
+    }
+
+    /**
+     * Alow threads wait for each other to reach a common barrier point. This class does
+     * not park threads that are waiting for the barrier to trip, instead it spins. This
+     * makes it suitable for tests that use LockSupport.park or Thread.yield.
+     */
+    private static class Barrier {
+        private final int parties;
+        private final AtomicInteger count;
+        private volatile int generation;
+
+        Barrier(int parties) {
+            this.parties = parties;
+            this.count = new AtomicInteger(parties);
+        }
+
+        void await() {
+            int g = generation;
+            if (count.decrementAndGet() == 0) {
+                count.set(parties);
+                generation = g + 1;
+            } else {
+                while (generation == g) {
+                    Thread.onSpinWait();
+                }
+            }
+        }
+
+    }
+}