RFR: 8365526: Crash with null Symbol passed to SystemDictionary::resolve_or_null

[Tom Rodriguez]

On Thu, 20 Nov 2025 17:00:04 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> The vm was crashing because the constant pool couldn't find the resolution error in the ResolutionErrorEntry error field.
> 
> There are two uses of ResolutionErrorEntry in the ResolutionErrorTable.  The key to this table is {ConstantPool, cp-index}.   In this crash, multiple threads were racing to record nest_host_errors in the case where resolution failed.  In this case, there was already a ResolutionErrorEntry in the table for the constant pool resolution failure.  In the 'if' case of add_nest_host_error we check to see if there's already a nest_host_error assuming it's the same error, then the 'else' case was unconditionally adding a ResolutionErrorEntry with just the nest host message.  Calling HashTable::put() with this entry with just the nest host message, was overwriting the entry with the constant pool resolution error, ie. the other fields.  The crash happened in ConstantPool::throw_resolution_error() because the error field was overwritten (and leaked too).
> 
> Add a null check before calling ResolutionErrorEntry add entry.  Also added an assert that we only add a resolution error for nest host errors in the case of success since in the case of failure there will always already be a ResolutionErrorEntry for the failing constant pool and cp index and we don't want to overwrite that again.
> 
> Tested with submitted reproducer and tier1-4.

Thanks for tracking this down!  Looks good.

src/hotspot/share/classfile/systemDictionary.cpp line 1877:

> 1875:       // resolution succeeded but there's an error in this nest host.
> 1876:       assert(pool->resolved_klass_at(which) != nullptr, "klass is should be resolved if there is no entry");
> 1877:       ResolutionErrorTable::add_entry(pool, which, message);

I might be inclined to swap the cases.

if (entry == nullptr) {
    ...
} else if (entry->nest_host_error() == nullptr) {
    ...
}


Is there ever a situation where replacing an entry in ResolutionErrorTable is correct?  Maybe there should be a check for that somewhere?

-------------

Marked as reviewed by never (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28438#pullrequestreview-3493677260
PR Review Comment: https://git.openjdk.org/jdk/pull/28438#discussion_r2550445406