[Clp] Bug in ClpModel::gutsOfCopy (stable branch)

[Sebastian Theophil]

Hi,

there seems to be a bug in ClpModel::gutsOfCopy in the stable branch:

in lines 780 and following (i.e. if trueCopy && maximumRows_<0) there is
the following code:

  if (rhs.rowActivity_) {
	rowActivity_= ClpCopyOfArray(rhs.rowActivity_, numberRows_);
	columnActivity_=
ClpCopyOfArray(rhs.columnActivity_,numberColumns_);
	dual_= ClpCopyOfArray(rhs.dual_, numberRows_);
	reducedCost_= ClpCopyOfArray(rhs.reducedCost_, numberColumns_);
  } else {
	rowActivity_=NULL;
	columnActivity_=NULL;
	dual_=NULL;
	reducedCost_=NULL;
  }

which seems wrong because rhs.reducedCost_ and rhs.columnActivity_ can
be non zero if rhs has > 0 columns but zero rows:

	ClpSimplex solver;

	double afLower[] = { 0.0, 0.0 };
	double afUpper[] = { 1.0, 1.0 };
	double afObj[] = { 1.0, 0.0 };
	solver.addColumns( 2, afLower, afUpper, afObj, NULL );

	ClpSimplex solver2 = solver;

solver has a valid columnActivity_ array, solver2 does not. Unless
further columns are added to solver2, solving solver2 should cause a
crash.

>From what I see, ClpModel::gutsOfCopy should either not do any checks at
all and just ClpCopyOfArray every array, or it should enforce strict
consistency checks like

	if(numberRows_>0) {
           rowActivity_ = copy_and_assert_not_null(rhs.rowActivity_,
numberRows_)
           ...
      }
	if(numberColumns_>0) {
		...
	}

Regards,
Sebastian

--
Sebastian Theophil . stheophil at think-cell.com
Software Engineer
 
think-cell Software GmbH . Chausseestr. 8/E . 10115 Berlin, Germany 
http://www.think-cell.com . phone +49 30 666473-10 . toll-free (US) +1 800 891 8091
Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl . Amtsgericht Berlin-Charlottenburg, HRB 85229