Racecondition in ResourceLoader::_thread_load_function(void *p_userdata)

[0x0ACB]

Tested versions

4.3-editor

System information

Windows 10

Issue description

With commit 5640e8a the thread_load_mutex is unlocked after status is set to THREAD_LOAD_LOADED. However the code that is following that is still accessing the resource property. If a different thread calls ResourceLoader::load_threaded_get during that time resource will be set to nullptr in

godot/core/io/resource_loader.cpp

Line 660 in ee363af

memdelete(load_token);

Steps to reproduce

ResourceLoader::load_threaded_request(m_path, "", false);
....
const auto res = ResourceLoader::load_threaded_get_status(m_path);
if (res == ResourceLoader::THREAD_LOAD_LOADED)
{
    m_resource = ResourceLoader::load_threaded_get(m_path);
    finished();
    return true;
}
if (res != ResourceLoader::THREAD_LOAD_IN_PROGRESS)
{
    // need to remove the load task
    m_resource = ResourceLoader::load_threaded_get(m_path);
    m_error = String("Error loading resource {0}: {1}").format(varray(m_path, res));
    finished();
    return true;
}

Minimal reproduction project (MRP)

[Chaosus]

cc @RandomShaper

[RandomShaper]

Fixed by #94169.