CXX.CAST.OBJ_PTR_TO_OBJ_PTR

Cast between a pointer to object type and a pointer to a different object type.

The CXX.CAST.OBJ_PTR_TO_OBJ_PTR checker flags instances where the code casts a pointer to object into a pointer to a different object.

Vulnerability and risk

Casting a pointer to object into a pointer to a different object may result in a pointer that is not correctly aligned, which results in undefined behavior.

Mitigation and prevention

Avoid casting between a pointer to object type and a pointer to a different object type.

Vulnerable code example

Copy
  #include <stdio.h>
 
  void f(void)
  {
      if (sizeof(int) == sizeof(float)) {
          float f = 0.0f;
          int *ip = (int *)&f;
          (*ip)++;
          printf("float is %f\n", f);
         int i = 0;
         ip = (int *)&i;

     }
 }
 int main(int argc, char *argv[])
 {
     f();
     return 0;
 }

In this example, Klocwork reports a CXX.CAST.OBJ_PTR_TO_OBJ_PTR defect on Line 7, because accessing an object through a pointer of an incompatible type may result in undefined behavior.

Fixed code example

Copy
  #include <stdio.h>
 
  void f(void)
  {
      if (sizeof(int) == sizeof(float)) {
          float f = 0.0f;
          float *ip = &f;
          (*ip)++;
          printf("float is %f\n", f);
         int i = 0;

     }
 }
 int main(int argc, char *argv[])
 {
     f();
     return 0;
 }

In this fixed example, there is no cast between pointers of different object types.

Related checkers

  • MISRA.CAST.OBJ_PTR_TO_PTR.2012