gh-97728: Argument Clinic: Fix uninitialized variable in the Py_UNICO…

…DE converter (GH-97729) It affects function os.system() on Windows and Windows-specific modules winreg, _winapi, _overlapped, and _msi.
python · Oct 3, 2022 · 0ee9619a4cba58730c45e65d22288fadbf7680de · 0ee9619
1 parent e738b51
commit 0ee9619a4cba58730c45e65d22288fadbf7680de
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Showing 8 changed files with 46 additions and 42 deletions.
diff --git a/Lib/test/clinic.test b/Lib/test/clinic.test
@@ -1803,12 +1803,12 @@ static PyObject *
 test_Py_UNICODE_converter(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *return_value = NULL;
-    const Py_UNICODE *a;
-    const Py_UNICODE *b;
-    const Py_UNICODE *c;
-    const Py_UNICODE *d;
+    const Py_UNICODE *a = NULL;
+    const Py_UNICODE *b = NULL;
+    const Py_UNICODE *c = NULL;
+    const Py_UNICODE *d = NULL;
     Py_ssize_t d_length;
-    const Py_UNICODE *e;
+    const Py_UNICODE *e = NULL;
     Py_ssize_t e_length;
 
     if (!_PyArg_ParseStack(args, nargs, "O&O&O&u#Z#:test_Py_UNICODE_converter",
@@ -1833,7 +1833,7 @@ test_Py_UNICODE_converter_impl(PyObject *module, const Py_UNICODE *a,
                                const Py_UNICODE *b, const Py_UNICODE *c,
                                const Py_UNICODE *d, Py_ssize_t d_length,
                                const Py_UNICODE *e, Py_ssize_t e_length)
-/*[clinic end generated code: output=4d426808cdbb3ea3 input=064a3b68ad7f04b0]*/
+/*[clinic end generated code: output=9f34a249b3071fdd input=064a3b68ad7f04b0]*/
 
 
 /*[clinic input]

diff --git a/Misc/NEWS.d/next/Windows/2022-10-02-11-59-23.gh-issue-97728.dIdlPE.rst b/Misc/NEWS.d/next/Windows/2022-10-02-11-59-23.gh-issue-97728.dIdlPE.rst
@@ -0,0 +1,3 @@
+Fix possible crashes caused by the use of uninitialized variables when pass
+invalid arguments in :func:`os.system` on Windows and in Windows-specific
+modules (like ``winreg``).
diff --git a/Modules/clinic/_winapi.c.h b/Modules/clinic/_winapi.c.h
diff --git a/Modules/clinic/overlapped.c.h b/Modules/clinic/overlapped.c.h
diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
diff --git a/PC/clinic/_msi.c.h b/PC/clinic/_msi.c.h
diff --git a/PC/clinic/winreg.c.h b/PC/clinic/winreg.c.h
diff --git a/Tools/clinic/clinic.py b/Tools/clinic/clinic.py
@@ -3586,6 +3586,7 @@ def converter_init(self, *, accept={str}, zeroes=False):
                 self.converter = '_PyUnicode_WideCharString_Opt_Converter'
             else:
                 fail("Py_UNICODE_converter: illegal 'accept' argument " + repr(accept))
+        self.c_default = "NULL"
 
     def cleanup(self):
         if not self.length: