#vulnerable code 
                             protected void state4ENTITY_LENGTH() throws ProtocolException {
		// get content length
		int clen = Integer.parseInt(httpMessage.getFirstHeader(HttpHeaders.CONTENT_LENGTH.getName()).getValue());
		if (clen < 0) {
			throw new ProtocolException(ProtocolExceptionType.UNEXPECTED, "content length < 0");
		}
		
		// slice content value
		byte[] content = sliceByLength(clen);
		if (content == null) {
			return;
		}
		
		// render current request with entity
		entity.setContent(content);
		httpMessage.setEntity(entity);
		
		// to next state
		state = ENTITY_ENCODING;
	} 
                            #location 3 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             protected void state4ENTITY_LENGTH() throws ProtocolException {
		// get content length
		int clen = Integer.parseInt(httpMessage.getFirstHeader(HttpHeaderType.CONTENT_LENGTH.getName()).getValue());
		if (clen < 0) {
			throw new ProtocolException(ProtocolExceptionType.UNEXPECTED, "content length < 0");
		}
		
		// slice content value
		byte[] content = sliceByLength(clen);
		if (content == null) {
			return;
		}
		
		// render current request with entity
		entity.setContent(content);
		httpMessage.setEntity(entity);
		
		// to next state
		state = ENTITY_ENCODING;
	}