Synopsis

A possible NULL pointer is returned from a function, and immediately dereferenced without checking.

Enabled by default

Yes

Severity/Certainty

High/Medium

Full description

A pointer that might be NULL is returned from a function, and immediately dereferenced without checking.

Coding standards

Code examples

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

#include <string.h>

char *getenv(const char *name)
{
  return strcmp(name, "HOME")==0 ? "/" : NULL;
}

int ex(void)
{
  return *getenv("USER");  //getenv() might return 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 = malloc(sizeof(int));
  if (p != 0) {
    *p = 4;
  }
  return (int)p;
}