#fixed code
                                public BytePointer putString(String s, String charsetName)
            throws UnsupportedEncodingException {
        byte[] bytes = s.getBytes(charsetName);
        //capacity(bytes.length+1);
        put(bytes).put(bytes.length, (byte)0);
        return this;
    }
#vulnerable code 
                                public BytePointer putString(String s, String charsetName)
            throws UnsupportedEncodingException {
        byte[] bytes = s.getBytes(charsetName);
        //capacity(bytes.length+1);
        asBuffer().put(bytes).put((byte)0);
        return this;
    } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE