Prevent ifunc procs from being made shareable

etiennebarrie · etiennebarrie · commit 731a1e339ff8 · 2025-12-12T16:19:45.000+01:00
[Bug #21775]
diff --git a/test/ruby/test_ractor.rb b/test/ruby/test_ractor.rb
@@ -201,6 +201,18 @@ def test_max_cpu_1
     RUBY
   end
 
+  def test_symbol_proc_is_shareable
+    pr = :symbol.to_proc
+    assert_make_shareable(pr)
+  end
+
+  # [Bug #21775]
+  def test_ifunc_proc_not_shareable
+    h = Hash.new { self }
+    pr = h.to_proc
+    assert_unshareable(pr, /not supported yet/, exception: RuntimeError)
+  end
+
   def assert_make_shareable(obj)
     refute Ractor.shareable?(obj), "object was already shareable"
     Ractor.make_shareable(obj)
diff --git a/vm.c b/vm.c
@@ -1594,7 +1594,10 @@ rb_proc_ractor_make_shareable(VALUE self, VALUE replace_self)
         proc->is_isolated = TRUE;
     }
     else {
-        VALUE proc_self = vm_block_self(vm_proc_block(self));
+        const struct rb_block *block = vm_proc_block(self);
+        if (block->type != block_type_symbol) rb_raise(rb_eRuntimeError, "not supported yet");
+
+        VALUE proc_self = vm_block_self(block);
         if (!rb_ractor_shareable_p(proc_self)) {
             rb_raise(rb_eRactorIsolationError,
                      "Proc's self is not shareable: %" PRIsVALUE,
