From 35882523d101ea27490dc3a0b06c633daaf32353 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9rome=20Perrin?= <perrinjerome@gmail.com>
Date: Tue, 16 Jan 2024 18:49:24 +0900
Subject: [PATCH] [3.12] gh-113358: Fix rendering tracebacks with exceptions
 with a broken __getattr__ (GH-113359)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

(cherry picked from commit 04fabe22dd98b4d87f672254b743fbadd5206352)

Co-authored-by: Jérome Perrin <perrinjerome@gmail.com>
Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
---
 Lib/test/test_traceback.py                    | 15 +++++++++
 Lib/traceback.py                              |  6 +++-
 ...-12-21-14-55-06.gh-issue-113358.nRkiSL.rst |  1 +
 Python/pythonrun.c                            | 32 ++++++++++++++++++-
 4 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2023-12-21-14-55-06.gh-issue-113358.nRkiSL.rst

diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index e0ef9e03f1ff9f..61eb0a7ef93d7f 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -1654,6 +1654,21 @@ def __repr__(self):
         err_msg = "b'please do not show me as numbers'"
         self.assertEqual(self.get_report(e), vanilla + err_msg + '\n')
 
+        # an exception with a broken __getattr__ raising a non expected error
+        class BrokenException(Exception):
+            broken = False
+            def __getattr__(self, name):
+                if self.broken:
+                    raise ValueError(f'no {name}')
+                raise AttributeError(name)
+
+        e = BrokenException(123)
+        vanilla = self.get_report(e)
+        e.broken = True
+        self.assertEqual(
+            self.get_report(e),
+            vanilla + "Ignored error getting __notes__: ValueError('no __notes__')\n")
+
     def test_exception_with_multiple_notes(self):
         for e in [ValueError(42), SyntaxError('bad syntax')]:
             with self.subTest(e=e):
diff --git a/Lib/traceback.py b/Lib/traceback.py
index f61d5db0621ab5..8247d8ff8cd1e7 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -738,7 +738,11 @@ def __init__(self, exc_type, exc_value, exc_traceback, *, limit=None,
         # Capture now to permit freeing resources: only complication is in the
         # unofficial API _format_final_exc_line
         self._str = _safe_string(exc_value, 'exception')
-        self.__notes__ = getattr(exc_value, '__notes__', None)
+        try:
+            self.__notes__ = getattr(exc_value, '__notes__', None)
+        except Exception as e:
+            self.__notes__ = [
+                f'Ignored error getting __notes__: {_safe_string(e, '__notes__', repr)}']
 
         if exc_type and issubclass(exc_type, SyntaxError):
             # Handle SyntaxError's specially
diff --git a/Misc/NEWS.d/next/Library/2023-12-21-14-55-06.gh-issue-113358.nRkiSL.rst b/Misc/NEWS.d/next/Library/2023-12-21-14-55-06.gh-issue-113358.nRkiSL.rst
new file mode 100644
index 00000000000000..4afbbda9442676
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-12-21-14-55-06.gh-issue-113358.nRkiSL.rst
@@ -0,0 +1 @@
+Fix rendering tracebacks for exceptions with a broken ``__getattr__``.
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index f4c5d39c59b166..525df437b8070a 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1164,6 +1164,36 @@ print_exception_notes(struct exception_print_context *ctx, PyObject *notes)
     return -1;
 }
 
+static int
+get_exception_notes(struct exception_print_context *ctx, PyObject *value, PyObject **notes) {
+    PyObject *note = NULL;
+
+    if (_PyObject_LookupAttr(value, &_Py_ID(__notes__), notes) < 0) {
+        PyObject *type, *errvalue, *tback;
+        PyErr_Fetch(&type, &errvalue, &tback);
+        note = PyUnicode_FromFormat("Ignored error getting __notes__: %R", errvalue);
+        Py_XDECREF(type);
+        Py_XDECREF(errvalue);
+        Py_XDECREF(tback);
+        if (!note) {
+            goto error;
+        }
+        *notes = PyList_New(1);
+        if (!*notes) {
+            goto error;
+        }
+        if (PyList_SetItem(*notes, 0, note) < 0) {
+            Py_DECREF(*notes);
+            goto error;
+        }
+    }
+
+    return 0;
+error:
+    Py_XDECREF(note);
+    return -1;
+}
+
 static int
 print_exception(struct exception_print_context *ctx, PyObject *value)
 {
@@ -1183,7 +1213,7 @@ print_exception(struct exception_print_context *ctx, PyObject *value)
 
     /* grab the type and notes now because value can change below */
     PyObject *type = (PyObject *) Py_TYPE(value);
-    if (_PyObject_LookupAttr(value, &_Py_ID(__notes__), &notes) < 0) {
+    if (get_exception_notes(ctx, value, &notes) < 0) {
         goto error;
     }