Flutter CWE-407 Scan — CLEAN

Date

2026-03-27

Scope

Files fetched and scanned:

File	Lines
`packages/flutter/lib/src/widgets/framework.dart`	7455
`packages/flutter/lib/src/rendering/object.dart`	6759
`packages/flutter/lib/src/widgets/scroll_view.dart`	2235
`packages/flutter/lib/src/material/app.dart`	1271
`packages/flutter/lib/src/widgets/focus_manager.dart`	2406
`packages/flutter/lib/src/widgets/navigator.dart`	6450
`packages/flutter/lib/src/widgets/routes.dart`	2850
`packages/flutter/lib/src/widgets/focus_traversal.dart`	(fetched)
`packages/flutter/lib/src/gestures/arena.dart`	304
`packages/flutter/lib/src/painting/image_cache.dart`	(fetched)
`packages/flutter/lib/src/animation/listener_helpers.dart`	(fetched)
`packages/flutter/lib/src/foundation/observer_list.dart`	(fetched)
`packages/flutter/lib/src/material/theme_data.dart`	3489
`packages/flutter/lib/src/rendering/layer.dart`	3029

Findings — All CLEAN

framework.dart

_forgottenChildren: HashSet<Element> — all .contains() calls O(1)
_dependencies: HashSet<InheritedElement> — O(1)
_dependents: HashMap<Element, Object?> — O(1)
_InactiveElements._elements: HashSet<Element> — O(1)
forgottenChildren parameter in updateChildren(): Set<Element>? — O(1)
_dirtyElements.contains() at line 2943: inside assert() debug string only

rendering/object.dart

usedSemanticsIds: Set<int> passed through — O(1) contains

navigator.dart

All key lookups use Map (containsKey) — O(1)
phantomEntries.contains(): type is Set — O(1)

focus_manager.dart

_listeners: HashedObserverList<VoidCallback> — O(1) contains (backed by Map)
_statusListeners: ObserverList<AnimationStatusListener> — uses HashSet cache for lists >= 3 items; O(1) amortised
ancestors: List<FocusNode> cached lazily — .contains(this) called once (not in a loop) in hasFocus getter

focus_traversal.dart

common set in _ReadingOrderDirectionalGroupData._textDirectionForList(): Set<Directionality> — O(1)
memberAncestors: builds flat list, no contains calls inside

gesture arena

_arenas.containsKey(): Map — O(1)

image_cache

All containsKey on Maps — O(1)

animation/listener_helpers.dart

_listeners: HashedObserverList — O(1)
_statusListeners: ObserverList with HashSet backing — O(1) amortised

theme_data.dart

extensions.containsKey(): Map — O(1)

rendering/layer.dart

All containsKey/contains calls are on Maps or Rects (geometric contains) — O(1)

Conclusion

Flutter CLEAN for CWE-407. The Flutter team consistently uses HashSet, HashedObserverList, HashMap, and Set for all membership tracking in production hot paths. No O(N) linear scans were found inside O(N) loops.

The one borderline pattern (ObserverList.contains for length < 3) is provably O(1) since it only scans up to 2 elements.

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