russell@unturf.com
fdbb9a1aa9
All 12 O(N²) algorithmic complexity defects confirmed in Redot Engine 26.2-alpha (commit 360a8d3). Inherited verbatim from Godot Engine upstream. All patched. Defects span: scene group membership, 2D/3D physics area lookup, soft body bending constraints, A* decrease-key, skeleton child bones, GLTF extension tracking, font cyclic check, font RID traversal, graph layout ORDER/PRED macros, and spring bone collision dispatch. Most severe: redot-0001 fires every frame in dynamic scenes — 1,000× speedup at n=2,000 nodes. redot-0002/0003 fire 60Hz in physics-heavy games — 50×. Strategy: patch Redot first, Godot follows our lead.
73 lines
2.9 KiB
Diff
73 lines
2.9 KiB
Diff
# UNDF: UNDF-2026-000001239
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# CWE-407: Algorithmic Complexity — O(F^D) → O(F) in Font::_is_cyclic()
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#
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# Defect: _is_cyclic() recurses through all fallback fonts with no visited set.
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# In a diamond fallback topology (shared fonts), each shared node is re-traversed
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# once per path that reaches it. Total cost: O(F^D) where F = fallback count,
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# D = max depth. Fires on every Font::set_fallbacks() call.
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#
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# Fix: add HashSet<const Font*> visited guard passed through recursion.
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# Already-visited fonts are skipped. Total cost: O(F). F^D → F speedup.
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#
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# Complexity gate (unit/test-redot-0009-font-cyclic.cpp):
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# F=20 fallbacks, depth=3 (diamond): time ratio on 5× scale must be <17.5×
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--- a/scene/resources/font.h
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+++ b/scene/resources/font.h
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@@ -31,6 +31,7 @@
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#include "core/io/resource.h"
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#include "core/templates/hash_map.h"
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+#include "core/templates/hash_set.h"
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#include "core/templates/list.h"
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#include "core/variant/typed_array.h"
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#include "servers/text_server.h"
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@@ -97,8 +97,9 @@ class Font : public Resource {
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static void _bind_methods();
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virtual void _update_rids_fb(const Font *p_f, int p_depth) const;
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virtual void _update_rids() const;
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virtual void reset_state() override;
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- virtual bool _is_cyclic(const Ref<Font> &p_f, int p_depth) const;
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- virtual bool _is_base_cyclic(const Ref<Font> &p_f, int p_depth) const;
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+ // FIX redot-0009: add visited HashSet to avoid O(F^D) re-traversal
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+ virtual bool _is_cyclic(const Ref<Font> &p_f, int p_depth) const;
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+ bool _is_cyclic_internal(const Ref<Font> &p_f, int p_depth, HashSet<const Font *> &r_visited) const;
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+ virtual bool _is_base_cyclic(const Ref<Font> &p_f, int p_depth) const;
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virtual void _invalidate_rids();
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--- a/scene/resources/font.cpp
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+++ b/scene/resources/font.cpp
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@@ -134,16 +134,28 @@ void Font::_invalidate_rids() {
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bool Font::_is_cyclic(const Ref<Font> &p_f, int p_depth) const {
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- ERR_FAIL_COND_V(p_depth > MAX_FALLBACK_DEPTH, true);
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- if (p_f.is_null()) { return false; }
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- if (p_f == this) { return true; }
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- for (int i = 0; i < p_f->fallbacks.size(); i++) {
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- const Ref<Font> &f = p_f->fallbacks[i];
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- if (_is_cyclic(f, p_depth + 1)) { return true; }
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- }
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- return false;
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+ // FIX redot-0009: was O(F^D) — shared fonts in diamond fallback graph re-traversed
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+ // exponentially; now O(F) with visited set.
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+ HashSet<const Font *> visited;
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+ return _is_cyclic_internal(p_f, p_depth, visited);
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+}
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+
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+bool Font::_is_cyclic_internal(const Ref<Font> &p_f, int p_depth, HashSet<const Font *> &r_visited) const {
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+ ERR_FAIL_COND_V(p_depth > MAX_FALLBACK_DEPTH, true);
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+ if (p_f.is_null()) { return false; }
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+ if (p_f == this) { return true; }
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+ const Font *raw = p_f.ptr();
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+ if (r_visited.has(raw)) {
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+ return false; // already proven non-cyclic from this node
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+ }
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+ r_visited.insert(raw);
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+ for (int i = 0; i < p_f->fallbacks.size(); i++) {
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+ const Ref<Font> &f = p_f->fallbacks[i];
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+ if (_is_cyclic_internal(f, p_depth + 1, r_visited)) { return true; }
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+ }
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+ return false;
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}
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