Fix double-free of cached WASM module in fizzy vm_manager

src/koinos/vm_manager/fizzy/fizzy_vm_backend.cpp

@@ -193,7 +193,12 @@ void fizzy_runner::instantiate_module()
   uint32_t memory_pages_limit = 512; // Number of 64k pages allowed to allocate
 
   KOINOS_ASSERT( _instance == nullptr, runner_state_exception, "_instance was unexpectedly non-null" );
-  _instance = fizzy_resolve_instantiate( _module->get(),
+
+  // fizzy_resolve_instantiate takes ownership of the module it is given and
+  // frees it via fizzy_free_instance. The module here is owned by the cache's
+  // module_guard (which frees it via fizzy_free_module), so instantiate a clone
+  // instead — otherwise the same FizzyModule is freed twice (double-free).
+  _instance = fizzy_resolve_instantiate( fizzy_clone_module( _module->get() ),
                                          host_funcs,
                                          num_host_funcs,
                                          nullptr,

src/koinos/vm_manager/fizzy/module_cache.hpp

@@ -18,6 +18,12 @@ class module_guard
       _module( m )
   {}
 
+  // Sole owner of the raw FizzyModule; copying would free it twice.
+  module_guard( const module_guard& )            = delete;
+  module_guard& operator=( const module_guard& ) = delete;
+  module_guard( module_guard&& )                 = delete;
+  module_guard& operator=( module_guard&& )      = delete;
+
   ~module_guard()
   {
     fizzy_free_module( _module );