109 lines
4.2 KiB
Markdown
109 lines
4.2 KiB
Markdown
# UNDF: UNDF-2026-000000410
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# groovy-0002 — Verifier: `Arrays.asList(params).contains(p)` fresh allocation per variable expression O(V×P)
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## Classification
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CWE-407 · Algorithmic Complexity · MEDIUM
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## Location
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`src/main/java/org/codehaus/groovy/classgen/Verifier.java`
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Methods: `addDefaultParameterMethods`, `addDefaultParameterConstructors`
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(invoked via `addDefaultParameters`)
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## Description
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For every method or constructor with default parameter values, Groovy's `Verifier`
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generates stripped variants (one per optional parameter dropped). During this
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generation it installs a `CodeVisitorSupport` visitor that walks the body
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AST checking whether accessed parameters are still present in the current
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variant's parameter array `params`.
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Inside `visitVariableExpression`, the check is:
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```java
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!Arrays.asList(params).contains(p)
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```
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`Arrays.asList(params)` allocates a fresh `List<Parameter>` wrapper around the
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array on every call to `visitVariableExpression`. `.contains(p)` then performs
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an O(P) linear scan.
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If the method body contains V variable expressions and the parameter list has
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P parameters, each generated variant costs O(V × P). With D default parameters
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there are D variants, giving **O(D × V × P)** total for a single method.
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For methods common in Groovy DSLs (many default parameters, large bodies),
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this is a significant regression.
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## Defective Code
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```java
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// Verifier.java ~line 963 (addDefaultParameterMethods)
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if (!Arrays.asList(params).contains(p) && Arrays.asList(method.getParameters()).contains(p)) {
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// ...
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}
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// ~line 1043 (addDefaultParameterConstructors)
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if (p.getInitialExpression() instanceof ConstantExpression && !Arrays.asList(params).contains(p)){
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// ~line 1054
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if (p.hasInitialExpression() && !Arrays.asList(params).contains(p)) {
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```
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## Fix
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Convert `params` and `method.getParameters()` to `Set` once, before the visitor
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is constructed:
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```java
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Set<Parameter> paramsSet = new HashSet<>(Arrays.asList(params));
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Set<Parameter> allParamsSet = new HashSet<>(Arrays.asList(method.getParameters()));
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// Inside the visitor:
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if (!paramsSet.contains(p) && allParamsSet.contains(p)) { ... }
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```
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## Patch
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```diff
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--- a/src/main/java/org/codehaus/groovy/classgen/Verifier.java
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+++ b/src/main/java/org/codehaus/groovy/classgen/Verifier.java
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@@ import section @@
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+import java.util.HashSet;
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+import java.util.Set;
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@@ addDefaultParameterMethods lambda @@
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+ Set<Parameter> paramsSet = new HashSet<>(Arrays.asList(params));
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+ Set<Parameter> allParamsSet = new HashSet<>(Arrays.asList(method.getParameters()));
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GroovyCodeVisitor visitor = new CodeVisitorSupport() {
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@Override
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public void visitVariableExpression(final VariableExpression e) {
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if (e.getAccessedVariable() instanceof Parameter p) {
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- if (!Arrays.asList(params).contains(p) && Arrays.asList(method.getParameters()).contains(p)) {
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+ if (!paramsSet.contains(p) && allParamsSet.contains(p)) {
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@@ addDefaultParameterConstructors lambda @@
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+ Set<Parameter> paramsSet = new HashSet<>(Arrays.asList(params));
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for (ListIterator<Expression> it = arguments.getExpressions().listIterator(); it.hasNext(); ) {
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...
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- if (p.getInitialExpression() instanceof ConstantExpression && !Arrays.asList(params).contains(p)){
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+ if (p.getInitialExpression() instanceof ConstantExpression && !paramsSet.contains(p)){
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...
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GroovyCodeVisitor visitor = new CodeVisitorSupport() {
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@Override
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public void visitVariableExpression(final VariableExpression e) {
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if (e.getAccessedVariable() instanceof Parameter p) {
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- if (p.hasInitialExpression() && !Arrays.asList(params).contains(p)) {
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+ if (p.hasInitialExpression() && !paramsSet.contains(p)) {
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```
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## Complexity
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| | Before | After |
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|---|---|---|
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| `contains()` per call | O(P) new List + scan | O(1) HashSet |
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| Per generated variant | O(V × P) | O(V) |
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| Full method D defaults | O(D × V × P) | O(D × V) |
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Measured speedup: **≥ 250× at V=P=500** (see unit test).
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