[vtk-developers] [Paraview-developers] Bug found, then stuck...
Cory Quammen
cory.quammen at kitware.com
Sun Oct 22 10:06:08 EDT 2017
Cornelius,
Thank you for the detailed bug report and your findings!
vtk-developers at vtk.org (CC'ed) is a more appropriate list for this problem
as it is VTK code in question, but no worries. I have filed an issue with
your message in the VTK bug tracker for further tracking of this issue:
https://gitlab.kitware.com/vtk/vtk/issues/17153
Thanks!
Cory
On Sun, Oct 22, 2017 at 9:25 AM, Cornelis Bockemühl <
cornelis.bockemuehl at gmail.com> wrote:
> Dear VTK developers,
>
> First of all: Am I posting this maybe in the wrong mailing list??
>
> Anyway, here I go: In some project I am using the vtkIntersectPolyData
> filter. This works as expected many times, but from time to time I had
> crashes. I managed to track down these crashes to a little bug in that
> class that can be fixed by a very little change:
>
> in vtkIntersectionPolyDataFilter.cxx(14'1), replace
>
> lineBool = new bool[pd->GetNumberOfCells()];
>
>
> by
>
>
> lineBool = new bool[pd->GetNumberOfCells() + 1];
>
>
> The crash happened when this array was released (heap corruption), and it
> turned out that indeed under some circumstances the program writes one
> element more than there is allocated memory. This happens if further down
> in the GetSingleLoop function the "else if" branch is chosen inside the "if
> -- else if -- else" construct: Here the pd cells array is extended by one
> element.
>
> With the above fix the crash goes indeed away, but then later on the
> program throws an exception at vtkCellLinks.h(171):
>
> /**
>
> * Increment the count of the number of cells using the point.
>
> */
>
> void IncrementLinkCount(vtkIdType ptId) { this->Array[ptId].ncells++;};
>
>
> call stack at this point:
>
>
> 1 vtkCellLinks::IncrementLinkCount vtkCellLinks.h 171 0x7feced1c91a
> 2 vtkCellLinks::BuildLinks vtkCellLinks.cxx 153 0x7feced1a89a
> 3 vtkPolyData::BuildLinks vtkPolyData.cxx 1096 0x7fecf022ff1
> 4 debug_vtkIntersectionPolyDataFilter::Impl::SplitCell debug_vtkIntersectionPolyDataFilter.cxx 1007 0x7fec0c994e2
> 5 debug_vtkIntersectionPolyDataFilter::Impl::SplitMesh debug_vtkIntersectionPolyDataFilter.cxx 630 0x7fec0c971cc
> 6 debug_vtkIntersectionPolyDataFilter::RequestData debug_vtkIntersectionPolyDataFilter.cxx 2590 0x7fec0c94531
> 7 vtkPolyDataAlgorithm::ProcessRequest vtkPolyDataAlgorithm.cxx 90 0x7fecf556116
> 8 vtkExecutive::CallAlgorithm vtkExecutive.cxx 775 0x7fecf50eb55
> 9 vtkDemandDrivenPipeline::ExecuteData vtkDemandDrivenPipeline.cxx 491 0x7fecf50477c
> 10 vtkCompositeDataPipeline::ExecuteData vtkCompositeDataPipeline.cxx 179 0x7fecf4fc560
> 11 vtkDemandDrivenPipeline::ProcessRequest vtkDemandDrivenPipeline.cxx 274 0x7fecf503343
> 12 vtkStreamingDemandDrivenPipeline::ProcessRequest vtkStreamingDemandDrivenPipeline.cxx 328 0x7fecf588f67
> 13 vtkDemandDrivenPipeline::UpdateData vtkDemandDrivenPipeline.cxx 444 0x7fecf5042da
> 14 vtkStreamingDemandDrivenPipeline::Update vtkStreamingDemandDrivenPipeline.cxx 403 0x7fecf589412
> 15 vtkStreamingDemandDrivenPipeline::Update vtkStreamingDemandDrivenPipeline.cxx 366 0x7fecf58916c
> 16 vtkAlgorithm::Update vtkAlgorithm.cxx 1457 0x7fecf4e5348
> 17 vtkAlgorithm::Update vtkAlgorithm.cxx 1451 0x7fecf4e53b3
> 18 vtkCemTestIntersectionFilter::RequestData vtkCemTestIntersectionFilter.cxx 252 0x7fec0c84e7f
> 19 vtkPolyDataAlgorithm::ProcessRequest vtkPolyDataAlgorithm.cxx 90 0x7fecf556116
> 20 vtkExecutive::CallAlgorithm vtkExecutive.cxx 775 0x7fecf50eb55
> ... <More>
>
>
> Note that debug_vtkIntersectionPolyDataFilter is a copy of
> vtkIntersectionPolyDataFilter that I prepared to do my testing and add some
> debug output stuff etc. without interfering with the original code.
>
> I guess that the exception is again a consequence of adding that "cell" in
> GetSingleLoop, but now I must admit that my understanding of the internals
> of these geometric object classes is not yet good enough to see what went
> wrong! The code that needs checking by an expert seems to me the following
>
> vtkIntersectionPolyDataFilter.cxx(1536..1555):
>
> //There is one line attached to point. This means the intersection has
>
> //an open intersection loop (i.e. the surfaces are open and one does not
>
> //completeley intersect the other.
>
> //Make an artificial triangle loop in this case
>
> else if (pointCells->GetNumberOfIds() < 2)
>
> {
>
> vtkSmartPointer<vtkPolyData> currentpd =
>
> vtkSmartPointer<vtkPolyData>::New();
>
> vtkSmartPointer<vtkCellArray> currentcells =
>
> vtkSmartPointer<vtkCellArray>::New();
>
> currentcells = pd->GetLines();
>
> currentcells->InsertNextCell(2);
>
> currentcells->InsertCellPoint(nextPt);
>
> currentcells->InsertCellPoint(startPt);
>
> nextCell = currentcells->GetNumberOfCells()-1;
>
> currentpd->SetLines(currentcells);
>
> currentpd->SetPoints(pd->GetPoints());
>
> pd->DeepCopy(currentpd);
>
> pd->BuildLinks();
>
> }
>
>
> My guess is that this code is not yet good enough to properly insert the
> "cell" into pd...
>
> Any idea?
>
> Regards,
> Cornelis
>
> --
> Cornelis Bockemühl
> Basel, Schweiz
>
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--
Cory Quammen
Staff R&D Engineer
Kitware, Inc.
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