Page History

...

int func(int, int, int);
/* ... */

func(1, 2);
/* ... */
int func(int one, int two, int three){
  printf("%d %d %d", one, two, three);
  return 1;
}

Non-Compliant Code Example: (function pointers)

If a function pointer is set to refer to an incompatible function, invoking that function via the pointer may cause unexpected data to be taken from the process stack. As a result, unexpected data may be accessed by the called function.

Setting fn_ptr to point to add() could result in an unexpected value being used as parameter z in function add().

int add(int x, int y, int z) {
   return x + y + z;
}
int main(int argc, char *argv[]) {
   int (*fn_ptr) (int, int) ;
   int res;
   fn_ptr = add;
   res = fn_ptr(2, 3);  /* incorrect */
   /* ... */
   return 0;
}

Compliant Solution: (function pointers)

To correct this example, the declaration of fn_ptr is changed to accept three arguments.

int add(int x, int y, int z) {
   return x + y + z;
}

int main(int argc, char *argv[]) {
   int (*fn_ptr) (int, int, int) ;
   int res;
   fn_ptr = add;
   res = fn_ptr(2, 3, 4);
   /* ... */
   return 0;
}

Risk Assessment

Failing to include type information for function declarators can result in unexpected or unintended program behavior.

...