Question

I have a code,

class foo
{
   public:
     foo(){};
     ~foo(){};
};

class bar
{
   public:
      bar(){};
     ~bar(){};

      foo& Foo()
      {
         return m_foo;
      }

  private:
      foo m_foo; 
};

int main()
{
   bar *obj = new bar;

   if( /* true condition here */ )
   {
      foo lcFoo;
      lcFoo = obj->Foo(); // forgot this
   }

   delete obj;
}

Now I am getting a double free message from glibc when I call the “delete obj” part.

Please advice.

Thanks.

EDIT:
Thanks for the comments but this is the exact code I used. Do you think the problem is in the foo& Foo() function because it return the reference of the m_foo object and then when code jump to the if condition brace then that m_foo will be deleted?

Answer 1

There is no double free in the code you posted. I suspect that there is some pointer resource in foo, which is being copied as a pointer when foo is copied; yet is deleted in foo‘s destructor.

You might also want to change the contents of your if block to

foo& lcFoo = obj->Foo();

though the fact that you’re getting double frees here is indicative of larger issues than this.