From: yihong <zouzou0208@gmail.com>
Date: Mon, 15 Dec 2025 14:13:58 +0000 (+0800)
Subject: gh-142594: fix by property calls io.TextIOWrapper.detach (GH-142706)
X-Git-Tag: v3.15.0a3~33
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1d3854a19a376c1fc7f71e96c620f6bc2de8cd74;p=thirdparty%2FPython%2Fcpython.git

gh-142594: fix by property calls io.TextIOWrapper.detach (GH-142706)


Signed-off-by: yihong0618 <zouzou0208@gmail.com>
---

diff --git a/Lib/test/test_io/test_textio.py b/Lib/test/test_io/test_textio.py
index 6331ed2b9585..d725f9212cea 100644
--- a/Lib/test/test_io/test_textio.py
+++ b/Lib/test/test_io/test_textio.py
@@ -1544,6 +1544,22 @@ class CTextIOWrapperTest(TextIOWrapperTest, CTestCase):
         self.assertEqual([b"abcdef", b"middle", b"g"*chunk_size],
                          buf._write_stack)
 
+    def test_issue142594(self):
+        wrapper = None
+        detached = False
+        class ReentrantRawIO(self.RawIOBase):
+            @property
+            def closed(self):
+                nonlocal detached
+                if wrapper is not None and not detached:
+                    detached = True
+                    wrapper.detach()
+                return False
+
+        raw = ReentrantRawIO()
+        wrapper = self.TextIOWrapper(raw)
+        wrapper.close()  # should not crash
+
 
 class PyTextIOWrapperTest(TextIOWrapperTest, PyTestCase):
     shutdown_error = "LookupError: unknown encoding: ascii"
diff --git a/Misc/NEWS.d/next/Library/2025-12-14-18-30-48.gh-issue-142594.belDmD.rst b/Misc/NEWS.d/next/Library/2025-12-14-18-30-48.gh-issue-142594.belDmD.rst
new file mode 100644
index 000000000000..ee6a958933f7
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-12-14-18-30-48.gh-issue-142594.belDmD.rst
@@ -0,0 +1,2 @@
+Fix crash in ``TextIOWrapper.close()`` when the underlying buffer's
+``closed`` property calls :meth:`~io.TextIOBase.detach`.
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index 65da300abcf3..f98819525612 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -3150,6 +3150,9 @@ _io_TextIOWrapper_close_impl(textio *self)
     if (r > 0) {
         Py_RETURN_NONE; /* stream already closed */
     }
+    if (self->detached) {
+        Py_RETURN_NONE; /* gh-142594 null pointer issue */
+    }
     else {
         PyObject *exc = NULL;
         if (self->finalizing) {