boolean isValidLength() {

		long blockSize = block.getSize();
		if (length <= blockSize) {
			message = "Block size must be greater than " + Long.toHexString(blockSize);
			return false;
		}
		else if (length < 0 || length > Integer.MAX_VALUE) {
			message = "Expanded block is too large";
			return false;
		}
		return true;
	}
Return true if the length greater than the current block size.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/memory/ExpandBlockModel.java