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/util/logging/Handler/StreamHandlerLockingTest.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 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     8349206
+ * @summary j.u.l.Handler classes create deadlock risk via synchronized publish() method.
+ * @modules java.base/sun.util.logging
+ *          java.logging
+ * @build java.logging/java.util.logging.TestStreamHandler
+ * @run main/othervm StreamHandlerLockingTest
+ */
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.logging.Formatter;
+import java.util.logging.Handler;
+import java.util.logging.Level;
+import java.util.logging.LogRecord;
+import java.util.logging.TestStreamHandler;
+
+public class StreamHandlerLockingTest {
+    static class TestFormatter extends Formatter {
+        final Handler handler;
+
+        TestFormatter(Handler handler) {
+            this.handler = handler;
+        }
+
+        @Override
+        public String format(LogRecord record) {
+            if (Thread.holdsLock(handler)) {
+                throw new AssertionError("format() was called with handler locked (bad).");
+            }
+            return record.getMessage() + "\n";
+        }
+
+        @Override
+        public String getHead(Handler h) {
+            // This is currently true, and not easy to make unsynchronized.
+            if (!Thread.holdsLock(handler)) {
+                throw new AssertionError("getHead() expected to be called with handler locked.");
+            }
+            return "--HEAD--\n";
+        }
+
+        @Override
+        public String getTail(Handler h) {
+            // This is currently true, and not easy to make unsynchronized.
+            if (!Thread.holdsLock(handler)) {
+                throw new AssertionError("getTail() expected to be called with handler locked.");
+            }
+            return "--TAIL--\n";
+        }
+    }
+
+    private static final String EXPECTED_LOG =
+            String.join("\n", "--HEAD--", "Hello World", "Some more logging...", "And we're done!", "--TAIL--", "");
+
+    public static void main(String[] args) throws IOException {
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        TestStreamHandler handler = new TestStreamHandler(out);
+        TestFormatter formatter = new TestFormatter(handler);
+        handler.setFormatter(formatter);
+
+        handler.publish(log("Hello World"));
+        handler.publish(log("Some more logging..."));
+        handler.publish(log("And we're done!"));
+        handler.close();
+
+        // Post write callback should have happened once per publish call (with lock held).
+        if (handler.callbackCount != 3) {
+            throw new AssertionError("Unexpected callback count: " + handler.callbackCount);
+        }
+
+        String logged = out.toString("UTF-8");
+        if (!EXPECTED_LOG.equals(logged)) {
+            throw new AssertionError("Unexpected log contents: " + logged);
+        }
+    }
+
+    static LogRecord log(String msg) {
+        return new LogRecord(Level.INFO, msg);
+    }
+}