[FlopCpp] Crash/Security issue in FlopC++

[Gaetano Mendola]

Hi,
I'm in the process of writing some tests, and I'm experiencing random crashes.
The reason for it is quite simple. The crash can be obtained in the
following way:

void crash() {
  {
    MP_model myModel(new OsiCbcSolverInterface);
  }
  {
    MP_constraint myConstraint;
  }
}

what happens is the fact that MP_model has a current and a default model
initialized as follow:

MP_model& MP_model::default_model = *new MP_model(0);
MP_model* MP_model::current_model = &MP_model::default_model;

and MP_model on his CTOR updates the current model:

MP_Model::current_model = this;

MP_constraint on his constructor performs:

MP_model::current_model->add(*this);

As you can see in that crash function as soon the myModel scope is over then
the  "MP_model::current_model->add(*this);"  dereferences an invalid pointer.

The standard say this is an undefined behavior, it's also a security risk.

In order to properly fix it, I need to know the meaning of
current_model and the
default_model.

A quick fix is to put in the MP_model DTOR the following:

MP_model::current_model = &MP_model::default_model;

can someone enlighten me about the semantic of those two current_model and
default_model ?


Regards
Gaetano Mendola


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