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grt: fix cugr memory crash on out-of-bounds grid access #9739

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grt: fix cugr memory crash on out-of-bounds grid access #9739

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ef21d27
grt: fix cugr memory crash on out-of-bounds grid access
Divinesoumyadip Mar 12, 2026
d086195
style: run clang-format to fix CI
Divinesoumyadip Mar 12, 2026
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32 changes: 25 additions & 7 deletions src/grt/src/cugr/src/GridGraph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -250,6 +250,9 @@ GridGraph::GridGraph(const Design* design,
IntervalT GridGraph::rangeSearchGridlines(const int dimension,
const IntervalT& loc_interval) const
{
if (dimension < 0 || dimension > 1) {
return {0, 0};
}
IntervalT range;
range.Set(lower_bound(gridlines_[dimension].begin(),
gridlines_[dimension].end(),
Expand All @@ -270,13 +273,28 @@ IntervalT GridGraph::rangeSearchGridlines(const int dimension,
IntervalT GridGraph::rangeSearchRows(const int dimension,
const IntervalT& loc_interval) const
{
if (dimension < 0 || dimension > 1) {
return {0, 0};
}

// 1. Critical Empty Check: If the grid doesn't exist, exit early
if (gridlines_[dimension].empty()) {
return {0, 0};
}

const auto& lineRange = rangeSearchGridlines(dimension, loc_interval);
return {gridlines_[dimension][lineRange.low()] == loc_interval.low()
? lineRange.low()
: std::max(lineRange.low() - 1, 0),
gridlines_[dimension][lineRange.high()] == loc_interval.high()
? lineRange.high() - 1
: std::min(lineRange.high(), getSize(dimension) - 1)};

Comment on lines 274 to +286
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@gemini-code-assist gemini-code-assist bot Mar 12, 2026

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critical

While the clamping logic prevents out-of-bounds access for non-empty gridlines_, it doesn't handle the case where gridlines_[dimension] is empty. In this scenario, rangeSearchGridlines returns {0, 0}, max_idx becomes 0, and l and h are set to 0. The subsequent access gridlines_[dimension][l] will then cause a crash, which this pull request aims to prevent.

An early exit for an empty gridline vector is needed. With this check, the std::max in the max_idx calculation also becomes redundant and can be simplified.

  if (dimension < 0 || dimension > 1) return {0, 0};
  if (gridlines_[dimension].empty()) {
    return {0, 0};
  }
  const auto& lineRange = rangeSearchGridlines(dimension, loc_interval);
  
  // BOUNDARY SHIELD: Safely clamp to array boundaries
  const int max_idx = (int)gridlines_[dimension].size() - 1;
  const int l = std::min(lineRange.low(), max_idx);
  const int h = std::min(lineRange.high(), max_idx);

// 2. BOUNDARY SHIELD: Safely clamp to array boundaries
const int max_idx = (int) gridlines_[dimension].size() - 1;
const int l = std::min(lineRange.low(), max_idx);
const int h = std::min(lineRange.high(), max_idx);

// 3. Robust Return: Ensure we never return a negative index for either bound
return {
gridlines_[dimension][l] == loc_interval.low() ? l : std::max(l - 1, 0),
gridlines_[dimension][h] == loc_interval.high()
? std::max(0, h - 1)
: std::min(h, getSize(dimension) - 1)};
}

BoxT GridGraph::getCellBox(PointT point) const
Expand Down Expand Up @@ -908,4 +926,4 @@ void GridGraph::write(const std::string& heatmap_file) const
fout.close();
}

} // namespace grt
} // namespace grt
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