check for overflow in combinations_with_replacement (closes #23365)

Lib/test/test_itertools.py

@@ -344,8 +344,12 @@ class TestBasicOps(unittest.TestCase):
 
                 self.pickletest(cwr(values,r))                          # test pickling
 
-        # Test implementation detail:  tuple re-use
+    @support.bigaddrspacetest
+    def test_combinations_with_replacement_overflow(self):
+        with self.assertRaises(OverflowError):
+            combinations_with_replacement("AA", 2**30)
 
+        # Test implementation detail:  tuple re-use
     @support.impl_detail("tuple reuse is specific to CPython")
     def test_combinations_with_replacement_tuple_reuse(self):
         cwr = combinations_with_replacement

Misc/NEWS

@@ -21,6 +21,9 @@ Library
 
 - Issue #23366: Fixed possible integer overflow in itertools.combinations.
 
+- Issue #23365: Fixed possible integer overflow in
+  itertools.combinations_with_replacement.
+
 
 What's New in Python 3.3.6?
 ===========================

Modules/itertoolsmodule.c

@@ -2659,6 +2659,10 @@ cwr_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         goto error;
     }
 
+    if (r > PY_SSIZE_T_MAX/sizeof(Py_ssize_t)) {
+        PyErr_SetString(PyExc_OverflowError, "r is too big");
+        goto error;
+    }
     indices = PyMem_Malloc(r * sizeof(Py_ssize_t));
     if (indices == NULL) {
         PyErr_NoMemory();