gh-96577: Fixes buffer overrun in _msi module (GH-96633)

(cherry picked from commit 4114bcc9ef7595a07196bcecf9c7d6d39f57f64d)

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

diff --git a/Misc/NEWS.d/next/Windows/2022-09-07-00-11-33.gh-issue-96577.kV4K_1.rst b/Misc/NEWS.d/next/Windows/2022-09-07-00-11-33.gh-issue-96577.kV4K_1.rst
new file mode 100644 (file)
index 0000000..6025e5c
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2022-09-07-00-11-33.gh-issue-96577.kV4K_1.rst
@@ -0,0 +1 @@
+Fixes a potential buffer overrun in :mod:`msilib`.

diff --git a/PC/_msi.c b/PC/_msi.c
index 01516e85ccff30b4839ca111b48bb417dbd5e057..3d4e4ef22c26ddf0fe9de2da1a6e95e0df574f95 100644 (file)
--- a/PC/_msi.c
+++ b/PC/_msi.c
@@ -360,7 +360,7 @@ msierror(int status)
     int code;
     char buf[2000];
     char *res = buf;
-    DWORD size = sizeof(buf);
+    DWORD size = Py_ARRAY_LENGTH(buf);
     MSIHANDLE err = MsiGetLastErrorRecord();
 
     if (err == 0) {
@@ -484,7 +484,7 @@ _msi_Record_GetString_impl(msiobj *self, unsigned int field)
     unsigned int status;
     WCHAR buf[2000];
     WCHAR *res = buf;
-    DWORD size = sizeof(buf);
+    DWORD size = Py_ARRAY_LENGTH(buf);
     PyObject* string;
 
     status = MsiRecordGetStringW(self->h, field, res, &size);