bpo-40957: Fix refleak in _Py_fopen_obj() (GH-20827)


Signed-off-by: Christian Heimes <christian@python.org>
(cherry picked from commit 9672912e8f90374fd31b37ca0fb7cefbc6f4c555)

Co-authored-by: Christian Heimes <christian@python.org>
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-06-12-12-21-54.bpo-40957.Z8n6I6.rst b/Misc/NEWS.d/next/Core and Builtins/2020-06-12-12-21-54.bpo-40957.Z8n6I6.rst
new file mode 100644
index 0000000..f99c374
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-06-12-12-21-54.bpo-40957.Z8n6I6.rst
@@ -0,0 +1 @@
+Fix refleak in _Py_fopen_obj() when PySys_Audit() fails
diff --git a/Python/fileutils.c b/Python/fileutils.c
index 439bc35..22e72bd 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -1461,6 +1461,7 @@
     path_bytes = PyBytes_AS_STRING(bytes);
 
     if (PySys_Audit("open", "Osi", path, mode, 0) < 0) {
+        Py_DECREF(bytes);
         return NULL;
     }