bpo-31095: fix potential crash during GC (GH-2974)

7 files changed, 24 insertions, 4 deletions

diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index aa582ed..adbe789 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -1717,6 +1717,8 @@ dequeiter_traverse(dequeiterobject *dio, visitproc visit, void *arg)
 static void
 dequeiter_dealloc(dequeiterobject *dio)
 {
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
+    PyObject_GC_UnTrack(dio);
     Py_XDECREF(dio->deque);
     PyObject_GC_Del(dio);
 }
@@ -2097,6 +2099,8 @@ static PyMemberDef defdict_members[] = {
 static void
 defdict_dealloc(defdictobject *dd)
 {
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
+    PyObject_GC_UnTrack(dd);
     Py_CLEAR(dd->default_factory);
     PyDict_Type.tp_dealloc((PyObject *)dd);
 }
diff --git a/Modules/_elementtree.c b/Modules/_elementtree.c
index 3537f19..857005a 100644
--- a/Modules/_elementtree.c
+++ b/Modules/_elementtree.c
@@ -627,6 +627,7 @@ element_gc_clear(ElementObject *self)
 static void
 element_dealloc(ElementObject* self)
 {
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
     PyObject_GC_UnTrack(self);
     Py_TRASHCAN_SAFE_BEGIN(self)
 
@@ -2076,6 +2077,8 @@ elementiter_dealloc(ElementIterObject *it)
 {
     Py_ssize_t i = it->parent_stack_used;
     it->parent_stack_used = 0;
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
+    PyObject_GC_UnTrack(it);
     while (i--)
         Py_XDECREF(it->parent_stack[i].parent);
     PyMem_Free(it->parent_stack);
@@ -2083,7 +2086,6 @@ elementiter_dealloc(ElementIterObject *it)
     Py_XDECREF(it->sought_tag);
     Py_XDECREF(it->root_element);
 
-    PyObject_GC_UnTrack(it);
     PyObject_GC_Del(it);
 }
 
diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
index da1d2e1..33761a4 100644
--- a/Modules/_functoolsmodule.c
+++ b/Modules/_functoolsmodule.c
@@ -113,6 +113,7 @@ partial_new(PyTypeObject *type, PyObject *args, PyObject *kw)
 static void
 partial_dealloc(partialobject *pto)
 {
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
     PyObject_GC_UnTrack(pto);
     if (pto->weakreflist != NULL)
         PyObject_ClearWeakRefs((PyObject *) pto);
@@ -1073,7 +1074,11 @@ lru_cache_clear_list(lru_list_elem *link)
 static void
 lru_cache_dealloc(lru_cache_object *obj)
 {
-    lru_list_elem *list = lru_cache_unlink_list(obj);
+    lru_list_elem *list;
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
+    PyObject_GC_UnTrack(obj);
+
+    list = lru_cache_unlink_list(obj);
     Py_XDECREF(obj->maxsize_O);
     Py_XDECREF(obj->func);
     Py_XDECREF(obj->cache);
diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index 42c7f79..ba33f8c 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -1084,6 +1084,8 @@ bytesiobuf_traverse(bytesiobuf *self, visitproc visit, void *arg)
 static void
 bytesiobuf_dealloc(bytesiobuf *self)
 {
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
+    PyObject_GC_UnTrack(self);
     Py_CLEAR(self->source);
     Py_TYPE(self)->tp_free(self);
 }
diff --git a/Modules/_json.c b/Modules/_json.c
index 6cc31c6..54fc90c 100644
--- a/Modules/_json.c
+++ b/Modules/_json.c
@@ -655,7 +655,8 @@ py_encode_basestring(PyObject* self UNUSED, PyObject *pystr)
 static void
 scanner_dealloc(PyObject *self)
 {
-    /* Deallocate scanner object */
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
+    PyObject_GC_UnTrack(self);
     scanner_clear(self);
     Py_TYPE(self)->tp_free(self);
 }
@@ -1778,7 +1779,8 @@ bail:
 static void
 encoder_dealloc(PyObject *self)
 {
-    /* Deallocate Encoder */
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
+    PyObject_GC_UnTrack(self);
     encoder_clear(self);
     Py_TYPE(self)->tp_free(self);
 }
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 1380c57..e8abcb2 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -2778,6 +2778,8 @@ context_clear(PySSLContext *self)
 static void
 context_dealloc(PySSLContext *self)
 {
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
+    PyObject_GC_UnTrack(self);
     context_clear(self);
     SSL_CTX_free(self->ctx);
 #ifdef OPENSSL_NPN_NEGOTIATED
@@ -4292,6 +4294,7 @@ static PyTypeObject PySSLMemoryBIO_Type = {
 static void
 PySSLSession_dealloc(PySSLSession *self)
 {
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
     PyObject_GC_UnTrack(self);
     Py_XDECREF(self->ctx);
     if (self->session != NULL) {
diff --git a/Modules/_struct.c b/Modules/_struct.c
index b5fbc43..69a1e99 100644
--- a/Modules/_struct.c
+++ b/Modules/_struct.c
@@ -1589,6 +1589,8 @@ typedef struct {
 static void
 unpackiter_dealloc(unpackiterobject *self)
 {
+    /* bpo-31095: UnTrack is needed before calling any callbacks */
+    PyObject_GC_UnTrack(self);
     Py_XDECREF(self->so);
     PyBuffer_Release(&self->buf);
     PyObject_GC_Del(self);