Fix heap-use-after-free in PrimaDelayCalc copy constructor#380
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maliberty wants to merge 1 commit into
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Fix heap-use-after-free in PrimaDelayCalc copy constructor#380maliberty wants to merge 1 commit into
maliberty wants to merge 1 commit into
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The copy constructor copied node_index_map_, a std::map<const ParasiticNode*, size_t, ParasiticNodeLess>. Copying the map reconstructs its red-black tree, which invokes the ParasiticNodeLess comparator and dereferences the ParasiticNode* keys. When a delay calculator is cloned for parallel delay calculation (GraphDelayCalc::findDelays -> FindVertexDelays -> ArcDelayCalc::copy), the source map can hold pointers to ParasiticNodes that were already freed because the net's parasitic network was rebuilt (e.g. during resizer repair). Dereferencing those freed keys is a heap-use-after-free. node_index_map_ is transient state: findNodeCount() clears and rebuilds it from the current parasitic network before any read, and the primary constructor leaves it default-constructed. Copying it is therefore both unnecessary and the sole source of the dangling-pointer dereference, so leave it default-constructed in the copy constructor as well. Signed-off-by: Matt Liberty <mliberty@precisioninno.com>
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This pull request modifies the copy constructor of PrimaDelayCalc to prevent copying node_index_map_. This avoids dereferencing potentially freed raw ParasiticNode pointers during copy operations, as the map is transient and rebuilt before use. There are no review comments to address, so I have no additional feedback to provide.
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The copy constructor copied node_index_map_, a
std::map<const ParasiticNode*, size_t, ParasiticNodeLess>. Copying the map reconstructs its red-black tree, which invokes the ParasiticNodeLess comparator and dereferences the ParasiticNode* keys.
When a delay calculator is cloned for parallel delay calculation (GraphDelayCalc::findDelays -> FindVertexDelays -> ArcDelayCalc::copy), the source map can hold pointers to ParasiticNodes that were already freed because the net's parasitic network was rebuilt (e.g. during resizer repair). Dereferencing those freed keys is a heap-use-after-free.
node_index_map_ is transient state: findNodeCount() clears and rebuilds it from the current parasitic network before any read, and the primary constructor leaves it default-constructed. Copying it is therefore both unnecessary and the sole source of the dangling-pointer dereference, so leave it default-constructed in the copy constructor as well.