Error in creating stack header file. In C - c

Question

#include <stdbool.h>
#include <stdlib.h>
typedef struct Node{
void *data;
struct Node *next;
}node;
typedef struct Stack{
node *top;
}stack;
bool push (stack *s , void *val)
{
node *n;
n = create_node (val);
if (n)
{
n->next = s->top;
s->top = n;
return true;
}
return false;
}
void* pop (stack *s)
{
node *temp;
void *x = NULL;
if (s->top)
{
x = s->top->data;
temp = s->top;
s->top = s->top->next;
free(temp);
}
return x;
}
void* peek (stack *s)
{
void *x = NULL;
if (s->top)
x = s->top->data;
return x;
}
node* create_node (void *val)
{
node *n;
n = (node*) malloc (sizeof(node));
if (n)
{
n->data = val;
n->next = NULL;
}
return n;
}
stack* create_stack (void)
{
stack *s;
s = (stack*) malloc (sizeof(stack));
if (s)
s->top = NULL;
return s;
}
I tried to write a header file for stack in C. I included this header file in another program. I added the header file #include"mystack.h"
I think the error is somewhere in passing void pointer but I don't know how to debug it.
The stack gets created successfully but as I try to push or pop the code terminates. I can't seem to find the error.
The code for calling program is,
#include <stdio.h>
#include <stdbool.h>
#include "mystack.h"
void main()
{
stack *s = NULL;
int *x;
int val;
bool res;
s = create_stack ();
printf ("Enter value to push : ");
scanf ("%d" , val);
res = push (s , &val);
if (res)
printf ("...PUSHED %d IN STACK...\n", *x);
else
printf ("...STACK OVERFLOW...\n");
free(s->top);
free(s);
}
The code stops after push operation is called.