I have a question about malloc free order

It doesn't matter the order.

If you reallocate malloc to a pointer of memory, you have to do the opposite of free. I think this is your intention.

For example, if you assign A to malloc and B of A->B to malloc, you should free B and then free A. If A is free, B remains in memory, but B is not able to free B because B's address is unknown (because it flew away).