Synopsis

Do not dereference null pointers.

Enabled by default

Yes

Severity/Certainty

High/High

Full description

Dereferencing a null pointer is undefined behavior. On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. This check is identical to PTR-null-assign.

Coding standards

Code examples

The following code example fails the check and will give a warning:

#include <stdlib.h>

int main(void) {
  int *p;
  p = NULL;
  return *p;  //dereference after
              //assignment to NULL
}

The following code example passes the check and will not give a warning about this issue:

#include <stdlib.h>

int main(void) {
  int *p;
  p = NULL;
  p = (int *)1;
  return *p;
}