commit 9f3ed3e213b30059087d059a7d1d3b2527fa8654
author Zackery Spytz <zspytz@gmail.com> Tue Oct 23 13:28:06 2018 -0600
committer Serhiy Storchaka <storchaka@gmail.com> Tue Oct 23 22:28:06 2018 +0300
tree 550b4aaa4b449f074832553262ab3696ad901df8
parent 82af0b63b07aa8d92b50098e382b458143cfc677

Fix error handling bugs in _elementtree.c. (GH-10060)

References could leak, NULL could be dereferenced, and the Expat parser could
be double freed when some errors raised.

Modules/_elementtree.c

diff --git a/Modules/_elementtree.c b/Modules/_elementtree.c
index f88315d..2f1c4c0 100644
--- a/Modules/_elementtree.c
+++ b/Modules/_elementtree.c
@@ -336,6 +336,9 @@
 get_attrib_from_keywords(PyObject *kwds)
 {
     PyObject *attrib_str = PyUnicode_FromString("attrib");
+    if (attrib_str == NULL) {
+        return NULL;
+    }
     PyObject *attrib = PyDict_GetItem(kwds, attrib_str);
 
     if (attrib) {
@@ -356,10 +359,10 @@
 
     Py_DECREF(attrib_str);
 
-    /* attrib can be NULL if PyDict_New failed */
-    if (attrib)
-        if (PyDict_Update(attrib, kwds) < 0)
-            return NULL;
+    if (attrib != NULL && PyDict_Update(attrib, kwds) < 0) {
+        Py_DECREF(attrib);
+        return NULL;
+    }
     return attrib;
 }
 
@@ -592,10 +595,9 @@
         attrib = PyDict_Copy(attrib);
         if (!attrib)
             return NULL;
-        if (kwds) {
-            if (PyDict_Update(attrib, kwds) < 0) {
-                return NULL;
-            }
+        if (kwds != NULL && PyDict_Update(attrib, kwds) < 0) {
+            Py_DECREF(attrib);
+            return NULL;
         }
     } else if (kwds) {
         /* have keyword args */
@@ -1871,7 +1873,6 @@
              * scheduled for removal.
             */
             if (!(recycle = PyList_New(slicelen))) {
-                PyErr_NoMemory();
                 return -1;
             }
 
@@ -1911,7 +1912,7 @@
             self->extra->length -= slicelen;
 
             /* Discard the recycle list with all the deleted sub-elements */
-            Py_XDECREF(recycle);
+            Py_DECREF(recycle);
             return 0;
         }
 
@@ -3338,7 +3339,6 @@
         if (!target) {
             Py_CLEAR(self->entity);
             Py_CLEAR(self->names);
-            EXPAT(ParserFree)(self->parser);
             return -1;
         }
     }