bpo-31455: Fix an assertion failure in ElementTree.XMLParser(). (#3545)
* Avoid calling "PyObject_GetAttrString()" (and potentially executing user code) with a live exception set.
* Ignore only AttributeError on attribute lookups in ElementTree.XMLParser() and propagate all other exceptions.
diff --git a/Modules/_elementtree.c b/Modules/_elementtree.c
index 98d5e7f..28d0181 100644
--- a/Modules/_elementtree.c
+++ b/Modules/_elementtree.c
@@ -3260,6 +3260,18 @@
return (PyObject *)self;
}
+static int
+ignore_attribute_error(PyObject *value)
+{
+ if (value == NULL) {
+ if (!PyErr_ExceptionMatches(PyExc_AttributeError)) {
+ return -1;
+ }
+ PyErr_Clear();
+ }
+ return 0;
+}
+
/*[clinic input]
_elementtree.XMLParser.__init__
@@ -3314,14 +3326,33 @@
self->target = target;
self->handle_start = PyObject_GetAttrString(target, "start");
+ if (ignore_attribute_error(self->handle_start)) {
+ return -1;
+ }
self->handle_data = PyObject_GetAttrString(target, "data");
+ if (ignore_attribute_error(self->handle_data)) {
+ return -1;
+ }
self->handle_end = PyObject_GetAttrString(target, "end");
+ if (ignore_attribute_error(self->handle_end)) {
+ return -1;
+ }
self->handle_comment = PyObject_GetAttrString(target, "comment");
+ if (ignore_attribute_error(self->handle_comment)) {
+ return -1;
+ }
self->handle_pi = PyObject_GetAttrString(target, "pi");
+ if (ignore_attribute_error(self->handle_pi)) {
+ return -1;
+ }
self->handle_close = PyObject_GetAttrString(target, "close");
+ if (ignore_attribute_error(self->handle_close)) {
+ return -1;
+ }
self->handle_doctype = PyObject_GetAttrString(target, "doctype");
-
- PyErr_Clear();
+ if (ignore_attribute_error(self->handle_doctype)) {
+ return -1;
+ }
/* configure parser */
EXPAT(SetUserData)(self->parser, self);