Assertion failure in timedelta() in case of bad __divmod__

[serhiy-storchaka]

BPO	31752
Nosy	@Yhg1s, @terryjreedy, @abalkin, @serhiy-storchaka, @orenmn, @mlouielu, @miss-islington
PRs	bpo-31752: Fix possible crash in timedelta constructor called with custom integers. #3947 [3.6] bpo-31752: Fix possible crash in timedelta constructor called with custom integers. (GH-3947) #4086 [2.7] bpo-31752: Fix possible crash in timedelta constructor called w… #4088 bpo-35021: Fix assertion failures in _datetimemodule.c. #9958 bpo-35021: Fixes assertion failures in _datetimemodule.c #10039 bpo-35021: Fixes assertion failures in _datetimemodule.c #10040 [3.7] bpo-35021: Fix assertion failures in _datetimemodule.c. (GH-10039) #10614 [3.6] bpo-35021: Fix assertion failures in _datetimemodule.c. (GH-10039) #10615 [2.7] bpo-35021: Fix assertion failures in _datetimemodule.c. (GH-10039) #10617

^{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 = <Date 2017-10-23.16:57:20.973>
created_at = <Date 2017-10-10.21:29:28.746>
labels = ['extension-modules', '3.7', 'type-crash']
title = 'Assertion failure in timedelta() in case of bad __divmod__'
updated_at = <Date 2018-11-20.19:56:41.169>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2018-11-20.19:56:41.169>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2017-10-23.16:57:20.973>
closer = 'serhiy.storchaka'
components = ['Extension Modules']
creation = <Date 2017-10-10.21:29:28.746>
creator = 'serhiy.storchaka'
dependencies = []
files = []
hgrepos = []
issue_num = 31752
keywords = ['patch']
message_count = 12.0
messages = ['304083', '304131', '304351', '304751', '304808', '304810', '304822', '327990', '330143', '330146', '330148', '330151']
nosy_count = 7.0
nosy_names = ['twouters', 'terry.reedy', 'belopolsky', 'serhiy.storchaka', 'Oren Milman', 'louielu', 'miss-islington']
pr_nums = ['3947', '4086', '4088', '9958', '10039', '10040', '10614', '10615', '10617']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue31752'
versions = ['Python 2.7', 'Python 3.6', 'Python 3.7']

[serhiy-storchaka]

The following code causes an assertion error in timedelta constructor.

from datetime import timedelta

class BadInt(int):
    def __mul__(self, other):
        return Prod()

class Prod:
    def __radd__(self, other):
        return Sum()

class Sum:
    def __divmod__(self, other):
        return (0, -1)

timedelta(hours=BadInt(1))

Result:

python: /home/serhiy/py/cpython/Modules/_datetimemodule.c:1573: microseconds_to_delta_ex: Assertion `0 <= temp && temp < 1000000' failed.
Aborted (core dumped)

[mlouielu]

I got a different result in latest commit: eeb5ffd

➜  cpython git:(master) ✗ ./python test.py
Traceback (most recent call last):
  File "test.py", line 15, in <module>
    timedelta(hours=BadInt(1))
SystemError: <class 'datetime.timedelta'> returned NULL without setting an error

Do I miss some configure, I'm using ./configure --with-debug

[terryjreedy]

On Win10, installed 3.5.4, 3.6.3, 3.7.1a1 all raise SystemError.
3.6 and 3.7 repository debug builds raise AssertionError and Windows crash box. After the patch, a silent crash.

[serhiy-storchaka]

Unpatched Python should crash in debug build and can raise SystemError in release build.

I can't reproduce a crash on Windows after the patch.

[serhiy-storchaka]

New changeset 4ffd465 by Serhiy Storchaka in branch 'master':
bpo-31752: Fix possible crash in timedelta constructor called with custom integers. (bpo-3947)
4ffd465

[serhiy-storchaka]

New changeset 6e45d7b by Serhiy Storchaka (Miss Islington (bot)) in branch '3.6':
bpo-31752: Fix possible crash in timedelta constructor called with custom integers. (GH-3947) (bpo-4086)
6e45d7b

[serhiy-storchaka]

New changeset 5ef883b by Serhiy Storchaka in branch '2.7':
[2.7] bpo-31752: Fix possible crash in timedelta constructor called with custom integers. (GH-3947) (bpo-4088)
5ef883b

[Yhg1s]

This patch includes assertions that are easily triggered from user code: https://bugs.python.org/issue35021

[serhiy-storchaka]

New changeset 3ec0f49 by Serhiy Storchaka in branch 'master':
bpo-35021: Fix assertion failures in _datetimemodule.c. (GH-10039)
3ec0f49

[miss-islington]

New changeset d57ab8a by Miss Islington (bot) in branch '3.7':
bpo-35021: Fix assertion failures in _datetimemodule.c. (GH-10039)
d57ab8a

[miss-islington]

New changeset 7a0d964 by Miss Islington (bot) in branch '3.6':
bpo-35021: Fix assertion failures in _datetimemodule.c. (GH-10039)
7a0d964