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#include <functional>
 
void f() {
  auto l = [](const int &j) { return j; };
  std::function<int(const int &)> fn(l);
 
  int i = 42;
  int j = fn(i);
}

Noncompliant Code Example

In this noncompliant code example, the constructor for the automatic variable s is not called because execution does not flow through the declaration of the local variable due to the goto statement. Because the constructor is not called, the lifetime for s has not begun. Therefore, calling S::f() uses the object outside of its lifetime and results in undefined behavior.

class S {
  int V;
public:
  S() : V(12) {} // Not a trivial constructor
  void f();
};
 
void f() {
  // ...
 
  goto bad_idea;
 
  // ...
  S s; // Control passes over the declaration, so initialization does not take place.
 
bad_idea:
  s.f();
}

Compliant Solution

This compliant solution ensures that s is properly initialized prior to performing the local jump:

class S {
  int V;
public:
  S() : V(12) {} // Not a trivial constructor
  void f();
};
 
void f() {
  S s;

  // ...

  goto bad_idea;

  // ...

bad_idea:
  s.f();
}

Risk Assessment

Referencing an object outside of its lifetime can result in an attacker being able to run arbitrary code.

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Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Related Guidelines

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