8277444: Data race between JvmtiClassFileReconstituter::copy_bytecodes and class linking

[chadrako]

A clean backport of https://bugs.openjdk.org/browse/JDK-8277444

This fixes a race condition that occurs when a class is simultaneously retransformed via the Instrumentation API and linked. This can lead to invalid bytecode which will cause a VerifyError. Even worse, if class verifying is turned off, which it is by default for java.* classes, this will cause the JVM to crash/segfault.

The included test test/jdk/java/lang/instrument/RetransformBigClassTest.java fails before the patch and passes after`

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Progress

• JDK-8277444 needs maintainer approval
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8277444: Data race between JvmtiClassFileReconstituter::copy_bytecodes and class linking (Bug - P4 - Requested)

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[chadrako]

Waiting to request maintainer approval until backport is merged in newer JDKs

[bridgekeeper]

👋 Welcome back chadrako! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @chadrako This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 00: Full (454656d3)

[chadrako]

/approval request A clean backport that fixes a race condition that occurs when a class is simultaneously retransformed via the Instrumentation API and linked. This can lead to invalid bytecode which will cause a VerifyError. Even worse, if class verifying is turned off, which it is by default for java.* classes, this will cause the JVM to crash/segfault. The included test test/jdk/java/lang/instrument/RetransformBigClassTest.java fails before the patch and passes after

[openjdk]

@chadrako
8277444: The approval request has been created successfully.

[GoeLin]

Hi @chadrako
this seems to be a quite unlikely situation. Also, it's a long standing bug. I would prefer to give it some time in 25&26 before backporting it to LTS releases already widely used.