Page History

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const char *p;
void dont_do_this(void) {
  const char c_str[] = "This will change";
  p = c_str; /* Dangerous */
  /* ... */
}

void innocuous(void) {
  const char c_str[] = "Surprise, surprise";
}
/* ... */

int main(void) {
  dont_do_this();
  innocuous();
  /* p might be pointing to "Surprise, surprise" */

  return 0;
}

Compliant Solution (Similar Scope)

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In this noncompliant code sample, the function squirrel_away() stores a pointer to local stack variable local into a location pointed to by function parameter ptr_param.  Because it can be assumed that the pointer variable to which ptr_param points remains alive upon Upon the return of squirrel_away()'s return, it is invalid for local to go out of scope the pointer ptr_param points to a variable that has an expired lifetime.

void squirrel_away(char **ptr_param) {
  char local[10];
  /* Initialize array */
  *ptr_param = local;
}

void rodent() {
  char *ptr;
  squirrel_away(&ptr);
  /* ptr is live but invalid here */
}

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