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Posted to issues@maven.apache.org by "kalayciburak (via GitHub)" <gi...@apache.org> on 2026/09/08 10:34:41 UTC
[PR] [SUREFIRE-3460] Don't NPE when StackWalkerStrategy inits with a null TCCL [maven-surefire]
kalayciburak opened a new pull request, #3464:
URL: https://github.com/apache/maven-surefire/pull/3464
`StackWalkerStrategy.<clinit>` loaded `java.lang.StackWalker` through the current thread's TCCL. When that loader is `null` (user threads that cleared it, or the JVM `Attach Listener` while a dynamic agent is installed), `ReflectionUtils.tryLoadClass` threw an uncaught `NullPointerException`. That failed class initialization and every later reference became `NoClassDefFoundError: Could not initialize class ...StackWalkerStrategy`.
Because console capture walks the stack on every `println`, a write from a null-TCCL thread could poison the forked JVM. On 3.6.0 this also surfaces as a confusing Byte Buddy / BlockHound self-attach failure when the JDK prints the dynamic-agent warning from `Attach Listener`.
This change:
- treats a null `ClassLoader` as "not found" in `tryLoadClass`, and also swallows `RuntimeException` so a later NPE cannot poison `<clinit>`
- resolves `StackWalker` / `StackFrame` from `StackWalkerStrategy`'s defining loader (system loader if that is bootstrap `null`), since those types are JDK classes and do not need the TCCL
Fixes #3460
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Validation (JDK 21, Maven 3.9.11):
- `mvn -pl surefire-api -Dtest=ReflectionUtilsTest,StackTraceProviderTest test` — 23 tests, 0 failures
- `mvn -pl surefire-api test` — 217 tests, 0 failures, 6 skipped
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Re: [PR] [SUREFIRE-3460] Don't NPE when StackWalkerStrategy inits with a null TCCL [maven-surefire]
Posted by "olamy (via GitHub)" <gi...@apache.org>.
olamy merged PR #3464:
URL: https://github.com/apache/maven-surefire/pull/3464
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Re: [PR] [SUREFIRE-3460] Don't NPE when StackWalkerStrategy inits with a null TCCL [maven-surefire]
Posted by "elharo (via GitHub)" <gi...@apache.org>.
elharo commented on code in PR #3464:
URL: https://github.com/apache/maven-surefire/pull/3464#discussion_r3967723594
##########
surefire-api/src/main/java/org/apache/maven/surefire/api/report/StackWalkerStrategy.java:
##########
@@ -55,7 +55,13 @@ final class StackWalkerStrategy {
private static final Method FRAME_METHOD_NAME; // StackWalker.StackFrame.getMethodName() -> String
static {
- ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+ // java.lang.StackWalker is a JDK class; do not depend on the current thread's TCCL, which can be null
+ // (Attach Listener, user threads that cleared it). A null TCCL used to NPE in tryLoadClass and poison
Review Comment:
only describe current code, not what uied to happen
##########
surefire-api/src/main/java/org/apache/maven/surefire/api/util/ReflectionUtils.java:
##########
@@ -148,9 +148,12 @@ public static <T> T instantiateObject(String className, Class<?>[] types, Object
@SuppressWarnings("checkstyle:emptyblock")
public static Class<?> tryLoadClass(ClassLoader classLoader, String className) {
+ if (classLoader == null) {
+ return null;
+ }
try {
return classLoader.loadClass(className);
- } catch (NoClassDefFoundError | ClassNotFoundException ignore) {
+ } catch (NoClassDefFoundError | ClassNotFoundException | RuntimeException ignore) {
Review Comment:
return null should probably move into this catch block
Don't catch RuntimeException. Only catch more specific exceptions you actually expect. Otherwise we'll hide bugs we should know about
##########
surefire-api/src/main/java/org/apache/maven/surefire/api/report/StackWalkerStrategy.java:
##########
@@ -55,7 +55,13 @@ final class StackWalkerStrategy {
private static final Method FRAME_METHOD_NAME; // StackWalker.StackFrame.getMethodName() -> String
static {
- ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+ // java.lang.StackWalker is a JDK class; do not depend on the current thread's TCCL, which can be null
+ // (Attach Listener, user threads that cleared it). A null TCCL used to NPE in tryLoadClass and poison
Review Comment:
only describe current code, not what used to happen
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Re: [PR] [SUREFIRE-3460] Don't NPE when StackWalkerStrategy inits with a null TCCL [maven-surefire]
Posted by "kalayciburak (via GitHub)" <gi...@apache.org>.
kalayciburak commented on code in PR #3464:
URL: https://github.com/apache/maven-surefire/pull/3464#discussion_r3975777483
##########
surefire-api/src/test/java/org/apache/maven/surefire/api/report/StackTraceProviderTest.java:
##########
@@ -142,4 +142,18 @@ void strategyWalkAppliesExcludePredicate() {
assertThat(frames).noneMatch(frame -> frame.startsWith(StackWalkerStrategy.class.getName() + "#"));
assertThat(frames.get(0)).isEqualTo(getClass().getName() + "#strategyWalkAppliesExcludePredicate");
}
+
+ @Test
+ void getStackDoesNotThrowWhenContextClassLoaderIsNull() {
+ ClassLoader original = Thread.currentThread().getContextClassLoader();
Review Comment:
added a tiny IT, same repro as on the issue (null TCCL thread + one println). pushed
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Re: [PR] [SUREFIRE-3460] Don't NPE when StackWalkerStrategy inits with a null TCCL [maven-surefire]
Posted by "olamy (via GitHub)" <gi...@apache.org>.
olamy commented on code in PR #3464:
URL: https://github.com/apache/maven-surefire/pull/3464#discussion_r3975003461
##########
surefire-api/src/test/java/org/apache/maven/surefire/api/report/StackTraceProviderTest.java:
##########
@@ -142,4 +142,18 @@ void strategyWalkAppliesExcludePredicate() {
assertThat(frames).noneMatch(frame -> frame.startsWith(StackWalkerStrategy.class.getName() + "#"));
assertThat(frames.get(0)).isEqualTo(getClass().getName() + "#strategyWalkAppliesExcludePredicate");
}
+
+ @Test
+ void getStackDoesNotThrowWhenContextClassLoaderIsNull() {
+ ClassLoader original = Thread.currentThread().getContextClassLoader();
Review Comment:
Thanks for your pull request.
Could you please provide an IT test as well. A real as simple as possible project reproducing the issue
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