RFR: 8301876: Crash in DumpTimeClassInfo::add_verification_constraint

[Matias Saavedra Silva]

On Wed, 8 Feb 2023 07:26:13 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> When dumping the a dynamic CDS archive, we clone and restore the `SystemDictionaryShared::_dumptime_table` (see [JDK-8264735](https://bugs.openjdk.org/browse/JDK-8264735).)
> 
> The bug is that for generated classes such as ` jdk/proxy2/$Proxy16` that are excluded from the CDS dump, we incorrectly remove their `DumpTimeClassInfo` from the `_dumptime_table` clone. After the dynamic archive has finished dumping, there's a very small window of time where some Java code would be executed and cause ` jdk/proxy2/$Proxy16` to be verified. This will cause the following crash because we can't find a `DumpTimeClassInfo` for this class. 
> 
> 
> DumpTimeSharedClassTable::get_info()
> SystemDictionaryShared::get_info()
> SystemDictionaryShared::add_verification_constraint()
> VerificationType::is_reference_assignable_from()
> ClassVerifier::verify_exception_handler_table()
> ClassVerifier::verify_method()
> ClassVerifier::verify_class()
> Verifier::verify()
> InstanceKlass::link_class_impl() -- for  jdk/proxy2/$Proxy16
> 
> 
> The fix is simple -- always copy all  `DumpTimeClassInfo` when cloning  `_dumptime_table` .

Nice and simple, LGTM!

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Marked as reviewed by matsaave (Author).

PR: https://git.openjdk.org/jdk/pull/12467