fix for crash when a python operator or render engine was freed in the C code and then referenced from python.

now further access in python gives an exception at the line when the freed data is accessed.

6 files changed, 17 insertions, 5 deletions

diff --git a/source/blender/python/BPY_extern.h b/source/blender/python/BPY_extern.h
index 83a40ecc068..53bd128562a 100644
--- a/source/blender/python/BPY_extern.h
+++ b/source/blender/python/BPY_extern.h
@@ -80,6 +80,7 @@ int		BPY_button_exec(struct bContext *C, const char *expr, double *value, const
 int		BPY_string_exec(struct bContext *C, const char *expr);
 
 void	BPY_DECREF(void *pyob_ptr);	/* Py_DECREF() */
+void	BPY_RNA_DECREF_INVALIDATE(void *pyob_ptr);
 int		BPY_context_member_get(struct bContext *C, const char *member, struct bContextDataResult *result);
 void	BPY_context_set(struct bContext *C);
 void	BPY_context_update(struct bContext *C);
diff --git a/source/blender/python/intern/bpy_interface.c b/source/blender/python/intern/bpy_interface.c
index f6ab100ca1a..39621fcf390 100644
--- a/source/blender/python/intern/bpy_interface.c
+++ b/source/blender/python/intern/bpy_interface.c
@@ -510,6 +510,18 @@ void BPY_DECREF(void *pyob_ptr)
 	PyGILState_Release(gilstate);
 }
 
+void BPY_RNA_DECREF_INVALIDATE(void *pyob_ptr)
+{
+	PyGILState_STATE gilstate = PyGILState_Ensure();
+	const int do_invalidate = (Py_REFCNT((PyObject *)pyob_ptr) > 1);
+	Py_DECREF((PyObject *)pyob_ptr);
+	if (do_invalidate) {
+		pyrna_invalidate(pyob_ptr);
+	}
+	PyGILState_Release(gilstate);
+}
+
+
 /* return -1 on error, else 0 */
 int BPY_button_exec(bContext *C, const char *expr, double *value, const short verbose)
 {
diff --git a/source/blender/python/intern/bpy_rna.c b/source/blender/python/intern/bpy_rna.c
index 122cc76a3f2..170eeb9e2af 100644
--- a/source/blender/python/intern/bpy_rna.c
+++ b/source/blender/python/intern/bpy_rna.c
@@ -119,13 +119,11 @@ int pyrna_prop_validity_check(BPy_PropertyRNA *self)
 	return -1;
 }
 
-#if defined(USE_PYRNA_INVALIDATE_GC) || defined(USE_PYRNA_INVALIDATE_WEAKREF)
-static void pyrna_invalidate(BPy_DummyPointerRNA *self)
+void pyrna_invalidate(BPy_DummyPointerRNA *self)
 {
 	self->ptr.type = NULL; /* this is checked for validity */
 	self->ptr.id.data = NULL; /* should not be needed but prevent bad pointer access, just in case */
 }
-#endif
 
 #ifdef USE_PYRNA_INVALIDATE_GC
 #define FROM_GC(g) ((PyObject *)(((PyGC_Head *)g) + 1))
diff --git a/source/blender/python/intern/bpy_rna.h b/source/blender/python/intern/bpy_rna.h
index 1fb4b116872..880ef4c2185 100644
--- a/source/blender/python/intern/bpy_rna.h
+++ b/source/blender/python/intern/bpy_rna.h
@@ -207,6 +207,7 @@ int pyrna_array_contains_py(PointerRNA *ptr, PropertyRNA *prop, PyObject *value)
 int pyrna_write_check(void);
 void pyrna_write_set(int val);
 
+void pyrna_invalidate(BPy_DummyPointerRNA *self);
 int pyrna_struct_validity_check(BPy_StructRNA *pysrna);
 int pyrna_prop_validity_check(BPy_PropertyRNA *self);
 
diff --git a/source/blender/render/intern/source/external_engine.c b/source/blender/render/intern/source/external_engine.c
index 636b3205b23..9647b100d2d 100644
--- a/source/blender/render/intern/source/external_engine.c
+++ b/source/blender/render/intern/source/external_engine.c
@@ -138,7 +138,7 @@ void RE_engine_free(RenderEngine *engine)
 {
 #ifdef WITH_PYTHON
 	if (engine->py_instance) {
-		BPY_DECREF(engine->py_instance);
+		BPY_RNA_DECREF_INVALIDATE(engine->py_instance);
 	}
 #endif
 
diff --git a/source/blender/windowmanager/intern/wm.c b/source/blender/windowmanager/intern/wm.c
index a34d294461c..fa00ec63b31 100644
--- a/source/blender/windowmanager/intern/wm.c
+++ b/source/blender/windowmanager/intern/wm.c
@@ -78,7 +78,7 @@ void WM_operator_free(wmOperator *op)
 	if (op->py_instance) {
 		/* do this first in case there are any __del__ functions or
 		 * similar that use properties */
-		BPY_DECREF(op->py_instance);
+		BPY_RNA_DECREF_INVALIDATE(op->py_instance);
 	}
 #endif