data is still in memory after removing from stack in C

data is still in memory after removing from stack in C

i'm trying to improve my knowledge of C. for exercise i wrote stack data
structure. everything works fine if i push N items and then pop N items.
the problem is found when i try push a item again. because last removed
item is still in memory (i think this is a problem).
when i allocate memory for new path struct, last removed string is still
on address which was free after poping a data. so when new string is
pushed, then last removed and new string is joined.
can someone please check a code and tell me what i'm doing wrong. other
comments are also welcome. thanks.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 1000
struct path {
char curPath[FILENAME_MAX];
struct path *Next;
};
struct MyStack {
struct path *head;
int size;
};
int push(struct MyStack *, char *);
char * pop(struct MyStack *, char *);
int main() {
char path[N];
struct MyStack stack;
stack.head = NULL;
stack.size = 0;
push(&stack, "aaaaaaaaaaaa");
push(&stack, "bbbbbbbbbbbb");
pop(&stack, path);
printf("%s\n", path);
// output is:
// bbbbbbbbbbbb
path[0] = '\0';
push(&stack, "cccccccccccc");
pop(&stack, path);
printf("%s\n", path);
// output should be:
// cccccccccccc
// but it is not
// it is:
// bbbbbbbbbbbbcccccccccccc
return 0;
}
int push(struct MyStack *stack, char *path) {
if (strlen(path) > N) {
return -1;
}
struct path *p = (struct path*)malloc(sizeof(struct path));
if (p == NULL) {
return -1;
}
strcat((*p).curPath, path);
(*p).Next = (*stack).head;
(*stack).head = p;
(*stack).size++;
return 0;
}
char * pop(struct MyStack *stack, char *path) {
if ((*stack).size == 0) {
printf("can't pop from empty stack");
return NULL;
}
struct path *p;
p = (*stack).head;
(*stack).head = (*p).Next;
strcat(path, (*p).curPath);
free(p);
p = NULL;
(*stack).size--;
return path;
}