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
1 #include <stdio.h>
2
3 void f(void)
4 {
5 if (sizeof(int) == sizeof(float)) {
6 float f = 0.0f;
7 int *ip = (int *)&f;
8 (*ip)++;
9 printf("float is %f\n", f);
10 int i = 0;
11 ip = (int *)&i;
12
13 }
14 }
15 int main(int argc, char *argv[])
16 {
17 f();
18 return 0;
19 }
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
1 #include <stdio.h>
2
3 void f(void)
4 {
5 if (sizeof(int) == sizeof(float)) {
6 float f = 0.0f;
7 float *ip = &f;
8 (*ip)++;
9 printf("float is %f\n", f);
10 int i = 0;
11
12 }
13 }
14 int main(int argc, char *argv[])
15 {
16 f();
17 return 0;
18 }
In this fixed example, there is no cast between pointers of different object types.
Related checkers
- MISRA.CAST.OBJ_PTR_TO_PTR.2012
