Checking if a pointer is allocated memory or not

Question

Can we check whether a pointer passed to a function is allocated with memory or not in C?

I have wriiten my own function in C which accepts a character pointer -

Answer 1

One hack you can try is checking if your pointer points to stack allocated memory. This will not help you in general as the allocated buffer might be to small or the pointer points to some global memory section (.bss, .const, ...).

To perform this hack, you first store the address of the first variable in main(). Later, you can compare this address with the address of a local variable in your specific routine. All addresses between both addresses are located on the stack.