gh-148222 Fix Null dereference bugs at genericaliasobject.c

Misc/NEWS.d/next/Core_and_Builtins/2026-04-07-20-37-23.gh-issue-148222.uF4D4E.rst

@@ -0,0 +1,2 @@
+1. Add Add NULL check and fallback to ga_vectorcall
+2. Add Null check to _Py_make_parameters when_PyTuple_Resize fails and parameter is null

Objects/genericaliasobject.c

@@ -242,7 +242,7 @@ _Py_make_parameters(PyObject *args)
                     len += needed;
                     if (_PyTuple_Resize(&parameters, len) < 0) {
                         Py_DECREF(subparams);
-                        Py_DECREF(parameters);
+                        Py_XDECREF(parameters);
                         Py_XDECREF(tuple_args);
                         return NULL;
                     }
@@ -650,7 +650,14 @@ ga_vectorcall(PyObject *self, PyObject *const *args,
               size_t nargsf, PyObject *kwnames)
 {
     gaobject *alias = (gaobject *) self;
-    PyObject *obj = PyVectorcall_Function(alias->origin)(alias->origin, args, nargsf, kwnames);
+    vectorcallfunc origin_vectorcall = PyVectorcall_Function(alias->origin);
+    PyObject *obj;
+    if (origin_vectorcall != NULL) {
+        obj = origin_vectorcall(alias->origin, args, nargsf, kwnames);
+    } else {
+        /* Fallback to generic call path*/
+        obj = PyObject_Vectorcall(alias->origin, args, nargsf, kwnames);
+    }
     return set_orig_class(obj, self);
 }