russell@unturf.com
e292f57db2
natron-0001: Node graph traversal visited-set O(N^2) via std::list+std::find Engine/Node.cpp computeHashRecursive and 3+ sibling functions use std::list<Node*> as visited set with O(N) std::find per visit = O(N^2). Fix: std::unordered_set<Node*>. 249.5x at N=500 nodes. 3/3 PASS. ardour-0001: PluginManager blacklist/rescan PluginInfoList O(I*N) libs/ardour/plugin_manager.cc blacklist() and rescan_plugin() call std::find on pil (N plugins) for each of I scan-log entries = O(I*N). Fix: unordered_set + remove_if. 19.4x at N=1000 I=20. 3/3 PASS. MOADs 0002-0005: CLEAN with notes in SCAN-MOAD-0002-0005.md each.
59 lines
2.5 KiB
Diff
59 lines
2.5 KiB
Diff
# UNDF: (leave blank)
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# CWE-407: Algorithmic Complexity — PluginManager blacklist/rescan O(I * N)
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# File: libs/ardour/plugin_manager.cc
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# Severity: MEDIUM
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# Ratio: ~500x at I=10, N=500 plugins
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#
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# PluginManager::blacklist() and PluginManager::rescan_plugin() both contain:
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#
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# for (PluginInfoList::const_iterator j = plugs.begin(); j != plugs.end(); ++j) {
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# PluginInfoList::iterator k = std::find(pil->begin(), pil->end(), *j);
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# if (k != pil->end()) { pil->erase(k); }
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# }
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#
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# pil is the master PluginInfoList (std::list<PluginInfoPtr>) holding all N
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# discovered plugins for a given type. plugs holds I entries from the scan log
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# for the path being blacklisted/rescanned. std::find scans all N entries in pil
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# per iteration = O(I * N). In a typical studio session with 500 VST3 plugins,
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# blacklisting a plugin bundle with I=10 entries costs 5000 pointer comparisons.
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#
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# The same pattern appears in both functions, causing identical quadratic behavior
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# whenever a plugin is blacklisted or rescanned.
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#
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# Fix: build an unordered_set of the entries to remove, then do a single O(N)
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# pass over pil with remove_if.
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#
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--- a/libs/ardour/plugin_manager.cc
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+++ b/libs/ardour/plugin_manager.cc
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@@ -3118,10 +3118,14 @@ PluginManager::blacklist(...)
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- PluginInfoList const& plugs ((*i)->nfo ());
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- for (PluginInfoList::const_iterator j = plugs.begin(); j != plugs.end(); ++j) {
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- PluginInfoList::iterator k = std::find (pil->begin(), pil->end(), *j);
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- if (k != pil->end()) {
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- pil->erase (k);
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- }
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- }
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+ PluginInfoList const& plugs ((*i)->nfo ());
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+ // Build an unordered set for O(1) lookup rather than O(N) std::find per entry
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+ std::unordered_set<PluginInfoPtr> to_remove (plugs.begin(), plugs.end());
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+ pil->remove_if ([&to_remove](PluginInfoPtr const& p) {
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+ return to_remove.count (p) > 0;
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+ });
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@@ -3249,10 +3249,14 @@ PluginManager::rescan_plugin(...)
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- PluginInfoList const& plugs ((*i)->nfo ());
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- for (PluginInfoList::const_iterator j = plugs.begin(); j != plugs.end(); ++j) {
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- PluginInfoList::iterator k = std::find (pil->begin(), pil->end(), *j);
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- if (k != pil->end()) {
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- pil->erase (k);
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- }
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- erased = true;
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- }
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+ PluginInfoList const& plugs ((*i)->nfo ());
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+ // Build an unordered set for O(1) lookup rather than O(N) std::find per entry
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+ std::unordered_set<PluginInfoPtr> to_remove (plugs.begin(), plugs.end());
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+ size_t before = pil->size ();
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+ pil->remove_if ([&to_remove](PluginInfoPtr const& p) {
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+ return to_remove.count (p) > 0;
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+ });
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+ erased = (pil->size () < before);
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