commit a6296d34a478b4f697ea9db798146195075d496c
author INADA Naoki <methane@users.noreply.github.com> Thu Aug 24 14:55:17 2017 +0900
committer GitHub <noreply@github.com> Thu Aug 24 14:55:17 2017 +0900
tree 6a26d56297f7d85dd6a8f18bca96e0c4ffb60802
parent bf9075a0c55186d2f34df63e6c8512dd6414ff4b

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

Modules/_elementtree.c

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 @@
 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 @@
 {
     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 @@
     Py_XDECREF(it->sought_tag);
     Py_XDECREF(it->root_element);
 
-    PyObject_GC_UnTrack(it);
     PyObject_GC_Del(it);
 }