gh-155733: Validate string keys in partial.__setstate__

Author: pranavchoudhary-tech

Lib/functools.py

@@ -417,6 +417,9 @@ def __setstate__(self, state):
            (namespace is not None and not isinstance(namespace, dict))):
             raise TypeError("invalid partial state")
 
+        if kwds is not None and any(not isinstance(k, str) for k in kwds):
+            raise TypeError("keywords must be strings")
+
         if args and args[-1] is Placeholder:
             raise TypeError("trailing Placeholders are not allowed")
         phcount, merger = _partial_prepare_merger(args)

Lib/test/test_functools.py

@@ -167,6 +167,9 @@ def test_non_string_keywords(self):
         p.keywords[1] = 'x'
         with self.assertRaisesRegex(TypeError, "keywords must be strings"):
             p()
+        p2 = self.partial(capture)
+        with self.assertRaisesRegex(TypeError, "keywords must be strings"):
+            p2.__setstate__((capture, (), {1: 'x'}, None))
 
     def test_no_side_effects(self):
         # make sure there are no side effects that affect subsequent calls

Modules/_functoolsmodule.c

@@ -830,6 +830,16 @@ partial_setstate(PyObject *self, PyObject *state)
         PyErr_SetString(PyExc_TypeError, "invalid partial state");
         return NULL;
     }
+    if (kw != Py_None) {
+        Py_ssize_t pos = 0;
+        PyObject *key, *val;
+        while (PyDict_Next(kw, &pos, &key, &val)) {
+            if (!PyUnicode_Check(key)) {
+                PyErr_SetString(PyExc_TypeError, "keywords must be strings");
+                return NULL;
+            }
+        }
+    }
 
     Py_ssize_t nargs = PyTuple_GET_SIZE(fnargs);
     if (nargs && PyTuple_GET_ITEM(fnargs, nargs - 1) == pto->placeholder) {