In code that was added by JDK-8238358 there's a potentially malloc'ed string that is never freed.

    utfName = getUTF(env, name, buf, sizeof(buf));

The solution is to do what _defineClass1 and _defineClass2 is already doing and free utfName after use if it's non-NULL and different from buf (getUTF returns buf if the string fits):

    if (utfName != NULL && utfName != buf) {
        free(utfName);
    }