[Octave-bug-tracker] [bug #60101] symbfact crashes for dense matrices

[Rik]

Follow-up Comment #9, bug #60101 (project octave):

I've found the problem.  The code in symbfact.cc at the start of the function
is


      const SparseMatrix a = args(0).sparse_matrix_value ();
  if (args(0).isreal ())
    {
      //const SparseMatrix a = args(0).sparse_matrix_value ();
      A->nrow = a.rows ();
      A->ncol = a.cols ();
      A->p = a.cidx ();
      A->i = a.ridx ();
      A->nzmax = a.nnz ();
      A->xtype = CHOLMOD_REAL;

      if (a.rows () > 0 && a.cols () > 0)
        A->x = a.data ();
    }
  else if (args(0).iscomplex ())
    {
      const SparseComplexMatrix a = args(0).sparse_complex_matrix_value ();
      A->nrow = a.rows ();
      A->ncol = a.cols ();
      A->p = a.cidx ();
      A->i = a.ridx ();
      A->nzmax = a.nnz ();
      A->xtype = CHOLMOD_COMPLEX;

      if (a.rows () > 0 && a.cols () > 0)
        A->x = a.data ();
    }


A temporary variable 'a' is declared inside a block and then used to
initialize the cholmod_sparse matrix A.  But when execution proceeds out of
the block the variable goes out of scope and can be reclaimed by a runtime
garbage collector.

I made the simple change above of declaring the variable 'a' outside of a
block so it is available and that stops the segfaults.

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