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/langtools/tools/javac/linenumbers/NullCheckLineNumberTest.java

@@ -0,0 +1,82 @@
+/*
+ * @test /nodynamiccopyright/
+ * @bug 8172880
+ * @summary  Wrong LineNumberTable for synthetic null checks
+ */
+
+import java.lang.classfile.*;
+import java.lang.classfile.attribute.*;
+
+import java.io.IOException;
+import java.util.AbstractMap.SimpleEntry;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map.Entry;
+import java.util.Objects;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class NullCheckLineNumberTest {
+
+    //test data:
+    static class Test {
+
+        public Test() {
+            String a = "", b = null;
+
+            Stream.of("x")
+                  .filter(a::equals)
+                  .filter(b::equals)
+                  .count();
+        }
+
+    }
+
+    public static void main(String[] args) throws Exception {
+        List<Entry> actualEntries = findEntries();
+        List<Entry> expectedEntries = List.of(
+                new SimpleEntry<>(24, 0),
+                new SimpleEntry<>(25, 4),
+                new SimpleEntry<>(27, 9),
+                new SimpleEntry<>(28, 16),
+                new SimpleEntry<>(29, 32),
+                new SimpleEntry<>(30, 46),
+                new SimpleEntry<>(31, 52)
+        );
+        if (!Objects.equals(actualEntries, expectedEntries)) {
+            error(String.format("Unexpected LineNumberTable: %s", actualEntries.toString()));
+        }
+
+        try {
+            new Test();
+        } catch (NullPointerException npe) {
+            if (Arrays.stream(npe.getStackTrace())
+                      .noneMatch(se -> se.getFileName().contains("NullCheckLineNumberTest") &&
+                                       se.getLineNumber() == 29)) {
+                throw new AssertionError("Should go through line 29!");
+            }
+        }
+    }
+
+    static List<Entry> findEntries() throws IOException {
+        ClassModel self = ClassFile.of().parse(Objects.requireNonNull(Test.class.getResourceAsStream("NullCheckLineNumberTest$Test.class")).readAllBytes());
+        for (MethodModel m : self.methods()) {
+            if ("<init>".equals(m.methodName().stringValue())) {
+                CodeAttribute code_attribute = m.findAttribute(Attributes.code()).orElseThrow();
+                for (Attribute<?> at : code_attribute.attributes()) {
+                    if (at instanceof LineNumberTableAttribute lineAt) {
+                        return lineAt.lineNumbers().stream()
+                                     .map(e -> new SimpleEntry<> (e.lineNumber(), e.startPc()))
+                                     .collect(Collectors.toList());
+                    }
+                }
+            }
+        }
+        return null;
+    }
+
+    static void error(String msg) {
+        throw new AssertionError(msg);
+    }
+
+}