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.
2026-03-26 17:11:57 -04:00 · 2026-03-26 17:11:57 -04:00 · 0a580b313d
commit 0a580b313d
70422 changed files with 17213626 additions and 0 deletions
--- a/test/jdk/java/util/Random/DistinctSeeds.java
+++ b/test/jdk/java/util/Random/DistinctSeeds.java
@ -0,0 +1,87 @@
+/*
+ * 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.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+/*
+ * @test
+ * @bug 4949279 6937857
+ * @summary Independent instantiations of Random() have distinct seeds.
+ * @key randomness
+ */
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Random;
+
+public class DistinctSeeds {
+    public static void main(String[] args) throws Exception {
+        // Strictly speaking, it is possible for these to randomly fail,
+        // but the probability should be small (approximately 2**-48).
+        if (new Random().nextLong() == new Random().nextLong() ||
+            new Random().nextLong() == new Random().nextLong())
+            throw new RuntimeException("Random() seeds not unique.");
+
+        // Now try generating seeds concurrently
+        class RandomCollector implements Runnable {
+            long[] randoms = new long[1<<17];
+            public void run() {
+                for (int i = 0; i < randoms.length; i++)
+                    randoms[i] = new Random().nextLong();
+            }
+        }
+        final int threadCount = 2;
+        List<RandomCollector> collectors = new ArrayList<>();
+        List<Thread> threads = new ArrayList<>();
+        for (int i = 0; i < threadCount; i++) {
+            RandomCollector r = new RandomCollector();
+            collectors.add(r);
+            threads.add(new Thread(r));
+        }
+        for (Thread thread : threads)
+            thread.start();
+        for (Thread thread : threads)
+            thread.join();
+        int collisions = 0;
+        HashSet<Long> s = new HashSet<>();
+        for (RandomCollector r : collectors) {
+            for (long x : r.randoms) {
+                if (s.contains(x))
+                    collisions++;
+                s.add(x);
+            }
+        }
+        System.out.printf("collisions=%d%n", collisions);
+        if (collisions > 10)
+            throw new Error("too many collisions");
+    }
+}