bpo-32587: Fixes unsafe downcast in PC/winreg.c (GH-15766)

(cherry picked from commit ef66f31ce21cd759cc0c618c5c42ba6da0a06834)

Co-authored-by: Steve Dower <steve.dower@python.org>

diff --git a/PC/winreg.c b/PC/winreg.c
index 37bc2c72dcdee13db04c3c30a5693e26e7ffcd9a..72a7c380beefe1eecbf2a93f80610f7093188dbf 100644 (file)
--- a/PC/winreg.c
+++ b/PC/winreg.c
@@ -772,7 +772,7 @@ Reg2Py(BYTE *retDataBuf, DWORD retDataSize, DWORD typ)
                         return NULL;
                     }
                     PyList_SET_ITEM(obData, index, uni);
-                    len -= slen + 1;
+                    len -= Py_SAFE_DOWNCAST(slen + 1, size_t, int);
                 }
                 PyMem_Free(str);