Fix heap-buffer-overflow in HNSW visited bitmap - #83
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The visited bitmap was sized from TableStats::getTableCard(), an estimated (possibly stale) cardinality, and indexed without bounds checks by graph neighbor offsets in oneHopSearch and related paths. When the estimate was smaller than the actual max node offset this caused an ASan heap-buffer-overflow READ in VisitedState::contains (LadybugDB/ladybug#940). - Size the bitmap from the exact NodeTable::getNumTotalRows() instead of the estimated table cardinality. - Make VisitedState bounds-safe and auto-growing: contains() returns false for out-of-range offsets, add() grows geometrically while preserving existing marks. - Proactively resize the bitmap to the current row count in initLayerSearchState to cover growth between query init and search.
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Fixes LadybugDB/ladybug#940.
ASan reported a heap-buffer-overflow READ in
VisitedState::contains(viaOnDiskHNSWIndex::oneHopSearch): the visited bitmap was sized fromTableStats::getTableCard(), an estimated (possibly stale) cardinality, and then indexed without bounds checks by graph neighbor offsets.Changes:
initQueryHNSWSharedStatenow sizes the bitmap from the exactNodeTable::getNumTotalRows()instead of the estimated table cardinality.VisitedStateis now bounds-safe and auto-growing:contains()returns false for out-of-range offsets,add()grows the bitmap geometrically while preserving existing marks.initLayerSearchStateproactively resizes the bitmap to the current row count, covering table growth between query init and search.