[New-bugs-announce] [issue41654] Segfault when raising MemoryError

[Oleg Hoefling]

New submission from Oleg Hoefling <oleg.hoefling at gmail.com>:

First of all, I guess this is a somewhat obscure error that is unlikely to occur in a usual context, nevertheless IMO worth reporting. We observed this when unit-testing custom exception reporting mechanism, raising different exceptions in different contexts and then analyzing whether they are processed correctly.

This is a somewhat dull example I managed to extract from our tests:


from pathlib import Path
from unittest.mock import patch


class TestException(MemoryError):
    pass


class report_ctx:
    def __enter__(self):
        return self
    def __exit__(self, exc_type, exc_value, tb):
        report(exc_value)


class raises:
    def __init__(self, ex):
        self.ex = ex
    def __enter__(self):
        return self
    def __exit__(self, exc_type, exc_value, tb):
        return issubclass(exc_type, self.ex)


def report(ex):
    pass


def error():
    raise MemoryError


modname = Path(__file__).stem

for _ in range(10):
    with patch(f"{modname}.report"):
        with raises(MemoryError), report_ctx():
            raise MemoryError

        with raises(TestException):
            raise TestException

        with raises(MemoryError):
            error()

that yields:

Fatal Python error: Segmentation fault

Current thread 0x00007fcf0833b740 (most recent call first):
  File "/home/oleg.hoefling/projects/private/python-memoryerror-segfault/main.py", line 38 in <module>
  File "<frozen importlib._bootstrap>", line 228 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 790 in exec_module
  File "<frozen importlib._bootstrap>", line 680 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 986 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 1007 in _find_and_load
  File "/usr/lib64/python3.9/unittest/mock.py", line 1236 in _importer
  File "/usr/lib64/python3.9/unittest/mock.py", line 1564 in <lambda>
  File "/usr/lib64/python3.9/unittest/mock.py", line 1389 in __enter__
  File "/home/oleg.hoefling/projects/private/python-memoryerror-segfault/main.py", line 36 in <module>

----------
components: Interpreter Core
messages: 376028
nosy: hoefling
priority: normal
severity: normal
status: open
title: Segfault when raising MemoryError
type: crash
versions: Python 3.10, Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue41654>
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