python · erlend-aasland · Nov 24, 2022 · Mar 24, 2022 · Mar 24, 2022 · Mar 24, 2022
diff --git a/Lib/test/clinic.test b/Lib/test/clinic.test
@@ -3856,7 +3856,7 @@ test_vararg(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject
     };
     #undef KWTUPLE
     PyObject *argsbuf[2];
-    Py_ssize_t noptargs = 0 + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 1;
+    Py_ssize_t noptargs = Py_MIN(nargs, 1) + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 1;
     PyObject *a;
     PyObject *__clinic_args = NULL;
 
@@ -3875,7 +3875,7 @@ exit:
 
 static PyObject *
 test_vararg_impl(PyObject *module, PyObject *a, PyObject *args)
-/*[clinic end generated code: output=6661f3ca97d85e8c input=81d33815ad1bae6e]*/
+/*[clinic end generated code: output=e98d5fe6742888b8 input=81d33815ad1bae6e]*/
 
 /*[clinic input]
 test_vararg_with_default
@@ -3929,7 +3929,7 @@ test_vararg_with_default(PyObject *module, PyObject *const *args, Py_ssize_t nar
     };
     #undef KWTUPLE
     PyObject *argsbuf[3];
-    Py_ssize_t noptargs = 0 + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 1;
+    Py_ssize_t noptargs = Py_MIN(nargs, 1) + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 1;
     PyObject *a;
     PyObject *__clinic_args = NULL;
     int b = 0;
@@ -3958,7 +3958,7 @@ exit:
 static PyObject *
 test_vararg_with_default_impl(PyObject *module, PyObject *a, PyObject *args,
                               int b)
-/*[clinic end generated code: output=5fe3cfccb1bef781 input=6e110b54acd9b22d]*/
+/*[clinic end generated code: output=291e9a5a09831128 input=6e110b54acd9b22d]*/
 
 /*[clinic input]
 test_vararg_with_only_defaults

@@ -730,6 +730,15 @@ def test_parameters_not_permitted_after_slash_for_now(self):
     x: int
 """)
 
+    def test_parameters_no_more_than_one_vararg(self):
+        s = self.parse_function_should_fail("""
+module foo
+foo.bar
+   *vararg1: object
+   *vararg2: object
+""")
+        self.assertEqual(s, "Error on line 0:\nToo many var args\n")
+
     def test_function_not_at_column_0(self):
         function = self.parse_function("""
   module foo

diff --git a/Misc/NEWS.d/next/Tools-Demos/2022-08-11-09-58-15.gh-issue-64490.PjwhM4.rst b/Misc/NEWS.d/next/Tools-Demos/2022-08-11-09-58-15.gh-issue-64490.PjwhM4.rst
@@ -0,0 +1,6 @@
+Argument Clinic varargs bugfixes
+
+* Fix out-of-bounds error in :c:func:`!_PyArg_UnpackKeywordsWithVararg`.
+* Fix incorrect check which allowed more than one varargs in clinic.py.
+* Fix miscalculation of ``noptargs`` in generated code.
+
diff --git a/Python/getargs.c b/Python/getargs.c
@@ -2586,7 +2586,7 @@ _PyArg_UnpackKeywordsWithVararg(PyObject *const *args, Py_ssize_t nargs,
             current_arg = NULL;
         }
 
-        buf[i + vararg + 1] = current_arg;
+        buf[i + 1] = current_arg;
 
         if (current_arg) {
             --nkwargs;

@@ -712,7 +712,7 @@ def output_templates(self, f):
         vararg = NO_VARARG
         pos_only = min_pos = max_pos = min_kw_only = pseudo_args = 0
         for i, p in enumerate(parameters, 1):
-            if p.is_keyword_only() or vararg != NO_VARARG:
+            if p.is_keyword_only():
                 assert not p.is_positional_only()
                 if not p.is_optional():
                     min_kw_only = i - max_pos
@@ -1015,22 +1015,23 @@ def parser_body(prototype, *fields, declarations=''):
                     max_pos,
                     min_kw_only
                 )
+                nargs = "nargs"
             else:
                 args_declaration = "_PyArg_UnpackKeywordsWithVararg", "%s, %s, %s, %s" % (
                     min_pos,
                     max_pos,
                     min_kw_only,
                     vararg
                 )
+                nargs = f"Py_MIN(nargs, {max_pos})" if max_pos else "0"
             if not new_or_init:
                 flags = "METH_FASTCALL|METH_KEYWORDS"
                 parser_prototype = parser_prototype_fastcall_keywords
                 argname_fmt = 'args[%d]'
                 declarations = declare_parser(f)
                 declarations += "\nPyObject *argsbuf[%s];" % len(converters)
                 if has_optional_kw:
-                    pre_buffer = "0" if vararg != NO_VARARG else "nargs"
-                    declarations += "\nPy_ssize_t noptargs = %s + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - %d;" % (pre_buffer, min_pos + min_kw_only)
+                    declarations += "\nPy_ssize_t noptargs = %s + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - %d;" % (nargs, min_pos + min_kw_only)
                 parser_code = [normalize_snippet("""
                     args = %s(args, nargs, NULL, kwnames, &_parser, %s, argsbuf);
                     if (!args) {{
@@ -1047,7 +1048,7 @@ def parser_body(prototype, *fields, declarations=''):
                 declarations += "\nPyObject * const *fastargs;"
                 declarations += "\nPy_ssize_t nargs = PyTuple_GET_SIZE(args);"
                 if has_optional_kw:
-                    declarations += "\nPy_ssize_t noptargs = nargs + (kwargs ? PyDict_GET_SIZE(kwargs) : 0) - %d;" % (min_pos + min_kw_only)
+                    declarations += "\nPy_ssize_t noptargs = %s + (kwargs ? PyDict_GET_SIZE(kwargs) : 0) - %d;" % (nargs, min_pos + min_kw_only)
                 parser_code = [normalize_snippet("""
                     fastargs = %s(_PyTuple_CAST(args)->ob_item, nargs, kwargs, NULL, &_parser, %s, argsbuf);
                     if (!fastargs) {{