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Java: Add support for flow through side-effects on static fields. #16500

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Merged
aschackmull merged 2 commits into from
May 24, 2024
Merged

Java: Add support for flow through side-effects on static fields. #16500

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Java: Add support for flow through side-effects on static fields.
aschackmull May 15, 2024
1bc3f6b
Java: Add change note.
aschackmull May 15, 2024
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4 changes: 4 additions & 0 deletions java/ql/lib/change-notes/2024-05-15-static-field-side-effect.md
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---
category: majorAnalysis
---
* Added support for data flow through side-effects on static fields. For example, when a static field containing an array is updated.
5 changes: 4 additions & 1 deletion java/ql/lib/semmle/code/java/dataflow/internal/DataFlowPrivate.qll
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Expand Up @@ -40,8 +40,11 @@ private predicate fieldStep(Node node1, Node node2) {
exists(Field f |
// Taint fields through assigned values only if they're static
f.isStatic() and
f.getAnAssignedValue() = node1.asExpr() and
node2.(FieldValueNode).getField() = f
|
f.getAnAssignedValue() = node1.asExpr()
or
f.getAnAccess() = node1.(PostUpdateNode).getPreUpdateNode().asExpr()
)
or
exists(Field f, FieldRead fr |
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21 changes: 21 additions & 0 deletions java/ql/test/library-tests/dataflow/fields/G.java
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public class G {
static Object[] f;

void sink(Object o) { }

void runsink() {
sink(f[0]);
}

void test1() {
f[0] = new Object();
}

void test2() {
addObj(f);
}

void addObj(Object[] xs) {
xs[0] = new Object();
}
}
2 changes: 2 additions & 0 deletions java/ql/test/library-tests/dataflow/fields/flow.expected
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Expand Up @@ -29,3 +29,5 @@
| F.java:5:14:5:25 | new Object(...) | F.java:20:10:20:17 | f.Field1 |
| F.java:10:16:10:27 | new Object(...) | F.java:15:10:15:17 | f.Field1 |
| F.java:24:9:24:20 | new Object(...) | F.java:33:10:33:17 | f.Field1 |
| G.java:11:12:11:23 | new Object(...) | G.java:7:10:7:13 | ...[...] |
| G.java:19:13:19:24 | new Object(...) | G.java:7:10:7:13 | ...[...] |