Added check to accept version 61, throw error for higher

build.gradle

@@ -366,3 +366,11 @@ tasks.register('runPolDet', Exec) {
 }
 
 defaultTasks "buildJars"
+
+sourceSets {
+    test {
+        resources {
+            srcDirs = ['src/tests/resources']
+        }
+    }
+}

src/main/gov/nasa/jpf/jvm/ClassFile.java

@@ -46,6 +46,7 @@ public class ClassFile extends BinaryClassSource {
   public static final int METHOD_HANDLE = 15;
   public static final int METHOD_TYPE = 16;
   public static final int INVOKE_DYNAMIC = 18;
+  private static final int MAX_SUPPORTED_VERSION = 61;
 
   public static final int REF_GETFIELD = 1;
   public static final int REF_GETSTATIC = 2;
@@ -218,7 +219,7 @@ public String getRequestedTypeName(){
   public static final String  BOOTSTRAP_METHOD_ATTR = "BootstrapMethods";
 
   protected final static String[] stdClassAttrs = {
-    SOURCE_FILE_ATTR, DEPRECATED_ATTR, INNER_CLASSES_ATTR, DEPRECATED_ATTR, SIGNATURE_ATTR,
+    SOURCE_FILE_ATTR, DEPRECATED_ATTR, INNER_CLASSES_ATTR, SIGNATURE_ATTR,
     RUNTIME_INVISIBLE_ANNOTATIONS_ATTR, RUNTIME_VISIBLE_ANNOTATIONS_ATTR, RUNTIME_VISIBLE_TYPE_ANNOTATIONS_ATTR,
     ENCLOSING_METHOD_ATTR, BOOTSTRAP_METHOD_ATTR };
 
@@ -944,6 +945,10 @@ public void parse( ClassFileReader reader)  throws ClassParseException {
       // we don't do much with the version numbers yet
       int minor = readU2();
       int major = readU2();
+      if (major > MAX_SUPPORTED_VERSION) {
+        // this will throw ClassParseException if the major version java 18 or higher
+        error("Unsupported class file version: " + major);
+      }
 
       // get the const pool
       int cpCount = readU2();

src/tests/gov/nasa/jpf/jvm/FileVersionTest.java

@@ -0,0 +1,50 @@
+package gov.nasa.jpf.jvm;
+
+import gov.nasa.jpf.util.test.TestJPF;
+import gov.nasa.jpf.vm.ClassParseException;
+import org.junit.Test;
+
+import java.io.*;
+
+public class FileVersionTest extends TestJPF {
+
+    private static final String JAVA17_CLASS = "/TestClassJava17.class";
+    private static final String JAVA21_CLASS = "/TestClassJava21.class";
+
+    // loading a .class file into a byte array
+    private byte[] loadClassFile(String resourceName) throws IOException {
+        try (InputStream is = getClass().getResourceAsStream(resourceName)) {
+            if (is == null) throw new IOException("Resource not found: " + resourceName);
+
+            ByteArrayOutputStream bos = new ByteArrayOutputStream();
+            // we choose here buffer size 1024 cause its enough to read most .class files in one or two iterations
+            // smaller buffer size like 256 will require more operations and larger buffers will waster memory
+            // i'm not sure which is suitable for this since the test classes we complied is empty but i think both could work
+            byte[] buffer = new byte[1024];
+            int bytesRead;
+            while ((bytesRead = is.read(buffer)) != -1) {
+                bos.write(buffer, 0, bytesRead);
+            }
+            return bos.toByteArray();
+        }
+    }
+
+
+    @Test
+    public void testSupportedVersionJava17() throws IOException, ClassParseException {
+        byte[] classData = loadClassFile(JAVA17_CLASS);
+        ClassFile classFile = new ClassFile(classData);
+        ClassFileReader reader = new ClassFileReaderAdapter();
+        // this should pass with no exceptions
+        classFile.parse(reader);
+    }
+
+    @Test(expected = ClassParseException.class)
+    public void testUnsupportedVersionJava21() throws IOException, ClassParseException {
+        byte[] classData = loadClassFile(JAVA21_CLASS);
+        ClassFile classFile = new ClassFile(classData);
+        ClassFileReader reader = new ClassFileReaderAdapter();
+        // this should throw ClassParseException
+        classFile.parse(reader);
+    }
+}