[3.9] gh-96577: Fixes buffer overrun in _msi module (GH-96633) (GH-96657)

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 913d3b85abb5f5e639733fa3dfaabf7383ecbeab..fd68e1df07f7eb2d0e11ffb7f6c1d2efe556a2af 100644 (file)
--- a/PC/_msi.c
+++ b/PC/_msi.c
@@ -292,7 +292,7 @@ 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) {
@@ -386,7 +386,7 @@ record_getstring(msiobj* record, PyObject* args)
     unsigned int status;
     WCHAR buf[2000];
     WCHAR *res = buf;
-    DWORD size = sizeof(buf);
+    DWORD size = Py_ARRAY_LENGTH(buf);
     PyObject* string;
 
     if (!PyArg_ParseTuple(args, "I:GetString", &field))