#12017: Fix segfault in json.loads() while decoding highly-nested objects using the C accelerations.

1 files changed, 13 insertions, 2 deletions

diff --git a/Modules/_json.c b/Modules/_json.c
index 4da5e74..7a995a5 100644
--- a/Modules/_json.c
+++ b/Modules/_json.c
@@ -899,6 +899,7 @@ scan_once_unicode(PyScannerObject *s, PyObject *pystr, Py_ssize_t idx, Py_ssize_
 
     Returns a new PyObject representation of the term.
     */
+    PyObject *res;
     Py_UNICODE *str = PyUnicode_AS_UNICODE(pystr);
     Py_ssize_t length = PyUnicode_GET_SIZE(pystr);
     if (idx >= length) {
@@ -913,10 +914,20 @@ scan_once_unicode(PyScannerObject *s, PyObject *pystr, Py_ssize_t idx, Py_ssize_
                 next_idx_ptr);
         case '{':
             /* object */
-            return _parse_object_unicode(s, pystr, idx + 1, next_idx_ptr);
+            if (Py_EnterRecursiveCall(" while decoding a JSON object "
+                                      "from a unicode string"))
+                return NULL;
+            res = _parse_object_unicode(s, pystr, idx + 1, next_idx_ptr);
+            Py_LeaveRecursiveCall();
+            return res;
         case '[':
             /* array */
-            return _parse_array_unicode(s, pystr, idx + 1, next_idx_ptr);
+            if (Py_EnterRecursiveCall(" while decoding a JSON array "
+                                      "from a unicode string"))
+                return NULL;
+            res = _parse_array_unicode(s, pystr, idx + 1, next_idx_ptr);
+            Py_LeaveRecursiveCall();
+            return res;
         case 'n':
             /* null */
             if ((idx + 3 < length) && str[idx + 1] == 'u' && str[idx + 2] == 'l' && str[idx + 3] == 'l') {