Fix T94454: Python API curve to mesh use after free without depsgraph

This was caused by a mistake in eb0eb54d9644c5139, which removed
the clearing of the curve edit mode pointers that are set when creating
the temporary data for the conversion. If they are not cleared, the
generic ID free function will also free the edit mode data, which is
wrong when the source curve is in edit mode.

1 files changed, 15 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/mesh_convert.cc b/source/blender/blenkernel/intern/mesh_convert.cc
index 43242e3a093..12fa9d16fd1 100644
--- a/source/blender/blenkernel/intern/mesh_convert.cc
+++ b/source/blender/blenkernel/intern/mesh_convert.cc
@@ -901,6 +901,20 @@ static Object *object_for_curve_to_mesh_create(const Object *object)
   return temp_object;
 }
 
+static void object_for_curve_to_mesh_free(Object *temp_object)
+{
+  /* Clear edit mode pointers that were explicitly copied to the temporary curve. */
+  ID *final_object_data = static_cast<ID *>(temp_object->data);
+  if (GS(final_object_data->name) == ID_CU) {
+    Curve &curve = *reinterpret_cast<Curve *>(final_object_data);
+    curve.editfont = nullptr;
+    curve.editnurb = nullptr;
+  }
+
+  BKE_id_free(nullptr, temp_object->data);
+  BKE_id_free(nullptr, temp_object);
+}
+
 /**
  * Populate `object->runtime.curve_cache` which is then used to create the mesh.
  */
@@ -1003,8 +1017,7 @@ static Mesh *mesh_new_from_curve_type_object(const Object *object)
 
   Mesh *mesh = mesh_new_from_evaluated_curve_type_object(temp_object);
 
-  BKE_id_free(nullptr, temp_object->data);
-  BKE_id_free(nullptr, temp_object);
+  object_for_curve_to_mesh_free(temp_object);
 
   return mesh;
 }