malloc doesn't keep track accurately in all cases, which is why double free is possible in the first place.
with mempool implementation, you shouldn't be able to release a previously released chunk because the pointer to that chunk will be zeroed out. This requires one more level of indirection in accessing the memory, i.e pointer to a struct that contains the pointer to the memory, but is otherwise safe.
As of note that may be causing some confusion, im not referencing the standard linux mempool implementation. I have written custom ones with a lot of helper functions for safe memory access.
