Check for non-existing values in stack elements

Author: KostasTsiounis

closed/src/java.base/share/classes/openj9/internal/security/RestrictedSecurity.java

@@ -885,7 +885,11 @@ boolean isRestrictedServiceAllowed(Service service, boolean isServiceAdded) {
                         }
                         String stackElemModule = stackElement.getModuleName();
                         String stackElemFullClassName = stackElement.getClassName();
-                        String stackElemPackage = stackElemFullClassName.substring(stackElemFullClassName.lastIndexOf(".") + 1);
+                        int stackElemEnd = stackElemFullClassName.lastIndexOf(".");
+                        String stackElemPackage = null;
+                        if (stackElemEnd != -1) {
+                            stackElemPackage = stackElemFullClassName.substring(0, );
+                        }
                         String module;
                         switch (option) {
                             case "ModuleAndFullClassName":
@@ -895,7 +899,8 @@ boolean isRestrictedServiceAllowed(Service service, boolean isServiceAdded) {
                                 }
                                 module = moduleAndFullClassName[0];
                                 String fullClassName = moduleAndFullClassName[1];
-                                found = stackElemModule.equals(module) && stackElemFullClassName.equals(fullClassName);
+                                found = (stackElemModule != null) && stackElemModule.equals(module)
+                                        && stackElemFullClassName.equals(fullClassName);
                                 break;
                             case "ModuleAndPackage":
                                 String[] moduleAndPackage = value.split("/");
@@ -904,13 +909,14 @@ boolean isRestrictedServiceAllowed(Service service, boolean isServiceAdded) {
                                 }
                                 module = moduleAndPackage[0];
                                 String packageValue = moduleAndPackage[1];
-                                found = stackElemModule.equals(module) && stackElemFullClassName.equals(packageValue);
+                                found = (stackElemModule != null) && stackElemModule.equals(module)
+                                        && (stackElemPackage != null) && stackElemPackage.equals(packageValue);
                                 break;
                             case "FullClassName":
                                 found = stackElemFullClassName.equals(value);
                                 break;
                             case "Package":
-                                found = stackElemPackage.equals(value);
+                                found = (stackElemPackage != null) && stackElemPackage.equals(value);
                                 break;
                             default:
                                 printStackTraceAndExit("Incorrect option to match in constraint: " + constraint);