Fix use-after-free bug when processing a dynamic Python proto with extensions.#220
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Fix use-after-free bug when processing a dynamic Python proto with extensions.#220copybara-service[bot] wants to merge 0 commit intomainfrom
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Fix use-after-free bug when processing a dynamic Python proto with extensions.
When a dynamic Python proto with extensions is passed through pybind11_protobuf,
the C++ bridge creates a DescriptorPool backed by the Python pool. During
proto parsing on the C++ side, extension lookup calls back into the Python
pool via FindExtensionByNumber. If the intermediate FieldDescriptor wrapper
returned by FindExtensionByNumber is not kept alive while its
.fileattributeis accessed and serialized, the UPB runtime may free the wrapper before
DescriptorPoolDatabase::CopyToFileDescriptorProto finishes, leading to a
heap-use-after-free.
This change contains the fix and a regression test that crashes under ASan without
the fix and passes under ASan with the fix.