An assertion failure in test_pickle

[ZackerySpytz]

BPO	38384
Nosy	@taleinat, @serhiy-storchaka, @phmc, @ZackerySpytz, @iritkatriel
PRs	gh-82565: Fix a possible assertion failure in _pickle #16606

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-10-06.13:39:09.443>
labels = ['extension-modules', '3.10', '3.9', 'type-crash', '3.11']
title = 'An assertion failure in test_pickle'
updated_at = <Date 2021-10-19.09:07:52.229>
user = 'https://github.com/ZackerySpytz'

bugs.python.org fields:

activity = <Date 2021-10-19.09:07:52.229>
actor = 'iritkatriel'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Extension Modules']
creation = <Date 2019-10-06.13:39:09.443>
creator = 'ZackerySpytz'
dependencies = []
files = []
hgrepos = []
issue_num = 38384
keywords = ['patch']
message_count = 4.0
messages = ['354038', '354040', '357337', '404277']
nosy_count = 5.0
nosy_names = ['taleinat', 'serhiy.storchaka', 'pconnell', 'ZackerySpytz', 'iritkatriel']
pr_nums = ['16606']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue38384'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

Linked PRs

• GH-82565: Fixed a possible assertion error #103206
• [3.12] gh-82565: Add tests for pickle and unpickle with bad files (GH-16606) #112591
• [3.11] gh-82565: Add tests for pickle and unpickle with bad files (GH-16606) #112592

[ZackerySpytz]

When running test_pickle, I sometimes see an assertion failure.

./python -m test test_pickle
0:00:00 load avg: 1.04 Run tests sequentially
0:00:00 load avg: 1.04 [1/1] test_pickle
python: Objects/typeobject.c:3151: _PyType_Lookup: Assertion `!PyErr_Occurred()' failed.
Fatal Python error: Aborted

Current thread 0x00007f8158632140 (most recent call first):
File "/home/lubuntu2/cpython/Lib/test/pickletester.py", line 3400 in test_unpickling_buffering_readline
File "/home/lubuntu2/cpython/Lib/unittest/case.py", line 617 in _callTestMethod
File "/home/lubuntu2/cpython/Lib/unittest/case.py", line 663 in run
File "/home/lubuntu2/cpython/Lib/unittest/case.py", line 725 in __call__
File "/home/lubuntu2/cpython/Lib/unittest/suite.py", line 122 in run
File "/home/lubuntu2/cpython/Lib/unittest/suite.py", line 84 in __call__
File "/home/lubuntu2/cpython/Lib/unittest/suite.py", line 122 in run
File "/home/lubuntu2/cpython/Lib/unittest/suite.py", line 84 in __call__
File "/home/lubuntu2/cpython/Lib/test/support/testresult.py", line 162 in run
File "/home/lubuntu2/cpython/Lib/test/support/init.py", line 2032 in _run_suite
File "/home/lubuntu2/cpython/Lib/test/support/init.py", line 2128 in run_unittest
File "/home/lubuntu2/cpython/Lib/test/test_pickle.py", line 525 in test_main
File "/home/lubuntu2/cpython/Lib/test/libregrtest/runtest.py", line 234 in _runtest_inner2
File "/home/lubuntu2/cpython/Lib/test/libregrtest/runtest.py", line 270 in _runtest_inner
File "/home/lubuntu2/cpython/Lib/test/libregrtest/runtest.py", line 153 in _runtest
File "/home/lubuntu2/cpython/Lib/test/libregrtest/runtest.py", line 193 in runtest
File "/home/lubuntu2/cpython/Lib/test/libregrtest/main.py", line 417 in run_tests_sequential
File "/home/lubuntu2/cpython/Lib/test/libregrtest/main.py", line 515 in run_tests
File "/home/lubuntu2/cpython/Lib/test/libregrtest/main.py", line 687 in _main
File "/home/lubuntu2/cpython/Lib/test/libregrtest/main.py", line 634 in main
File "/home/lubuntu2/cpython/Lib/test/libregrtest/main.py", line 712 in main
File "/home/lubuntu2/cpython/Lib/test/main.py", line 2 in <module>
File "/home/lubuntu2/cpython/Lib/runpy.py", line 85 in _run_code
File "/home/lubuntu2/cpython/Lib/runpy.py", line 192 in _run_module_as_main
Aborted (core dumped)

In _Unpickler_SetInputStream(), _PyObject_LookupAttrId() is called three times in a row without any error handling.
If an exception occurs during the first or second call, _PyObject_LookupAttrId() will be called with a live exception.

[serhiy-storchaka]

I do not understand how you got an assertion failure. Did you interrupt tests with Ctrl-C?

[taleinat]

Good catch on this, Zackery!

For anyone readying this, Serhiy posted a minimal reproducer in a PR comment, and the PR now adds a test for this.

[iritkatriel]

Reproduced on 3.11 with Serhiy's reproducer:

class F:
 @property
 def read(self):
 1/0

import pickle
pickle.load(F())