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

…DE converter It affects function os.system() on Windows and Windows-specific modules winreg, _winapi, _overlapped, and _msi.
serhiy-storchaka · Oct 3, 2022 · Oct 2, 2022 · Oct 2, 2022 · Oct 2, 2022 · 96a7768d705bd51091204b78ed690d91e31d44e9
commit 96a7768d705bd51091204b78ed690d91e31d44e9
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
@@ -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: