Issue #17671: Fixed a crash when use non-initialized io.BufferedRWPair.

Based on patch by Stephen Tu.

1 files changed, 7 insertions, 2 deletions

diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 34c2bb97bd..7494646342 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -2305,9 +2305,14 @@ bufferedrwpair_dealloc(rwpair *self)
 static PyObject *
 _forward_call(buffered *self, _Py_Identifier *name, PyObject *args)
 {
-    PyObject *func = _PyObject_GetAttrId((PyObject *)self, name);
-    PyObject *ret;
+    PyObject *func, *ret;
+    if (self == NULL) {
+        PyErr_SetString(PyExc_ValueError,
+                        "I/O operation on uninitialized object");
+        return NULL;
+    }
 
+    func = _PyObject_GetAttrId((PyObject *)self, name);
     if (func == NULL) {
         PyErr_SetString(PyExc_AttributeError, name->string);
         return NULL;