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A possible double decref in _ctypes.c's PyCArrayType_new() #80602

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ZackerySpytz mannequin opened this issue Mar 25, 2019 · 6 comments
Closed

A possible double decref in _ctypes.c's PyCArrayType_new() #80602

ZackerySpytz mannequin opened this issue Mar 25, 2019 · 6 comments
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3.7 (EOL) end of life 3.8 only security fixes extension-modules C modules in the Modules dir topic-ctypes

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@ZackerySpytz
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ZackerySpytz mannequin commented Mar 25, 2019

BPO 36421
Nosy @vstinner, @serhiy-storchaka, @matrixise, @ZackerySpytz, @miss-islington
PRs
  • bpo-36421: Fix a possible double decref in _ctypes.c's PyCArrayType_new() #12530
  • [3.7] bpo-36421: Fix a possible double decref in _ctypes.c's PyCArrayType_new(). (GH-12530) #12533
  • [2.7] bpo-36421: Fix ref counting bugs in _ctypes.c's PyCArrayType_new() #12534
    		•

    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 2019-03-25.14:16:30.219>
created_at = <Date 2019-03-25.03:31:24.056>
labels = ['extension-modules', 'ctypes', '3.7', '3.8']
title = "A possible double decref in _ctypes.c's PyCArrayType_new()"
updated_at = <Date 2019-06-04.16:18:11.784>
user = 'https://github.com/ZackerySpytz'

    bugs.python.org fields:

    activity = <Date 2019-06-04.16:18:11.784>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2019-03-25.14:16:30.219>
closer = 'serhiy.storchaka'
components = ['Extension Modules', 'ctypes']
creation = <Date 2019-03-25.03:31:24.056>
creator = 'ZackerySpytz'
dependencies = []
files = []
hgrepos = []
issue_num = 36421
keywords = ['patch']
message_count = 6.0
messages = ['338779', '338782', '338787', '338791', '338798', '344598']
nosy_count = 5.0
nosy_names = ['vstinner', 'serhiy.storchaka', 'matrixise', 'ZackerySpytz', 'miss-islington']
pr_nums = ['12530', '12533', '12534']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue36421'
versions = ['Python 2.7', 'Python 3.7', 'Python 3.8']
    @ZackerySpytz
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    ZackerySpytz mannequin commented Mar 25, 2019

    In PyCArrayType_new(), type_attr is assigned to stgdict->proto. If the PyDict_Update() call fails in that function, type_attr will be decrefed an extra time when stgdict is deallocated.

    I'll create a PR for this issue.

    @ZackerySpytz ZackerySpytz mannequin added 3.7 (EOL) end of life 3.8 only security fixes extension-modules C modules in the Modules dir topic-ctypes labels Mar 25, 2019
    @matrixise
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    Hi Zackery,

    just one question, how did you detect this bug? in reading the code,
    with a tool (valgrind or sanitizer) or with a test?

    Have a nice day and thank you for the clarification.

    @serhiy-storchaka
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    New changeset 5e33378 by Serhiy Storchaka (Zackery Spytz) in branch 'master':
    bpo-36421: Fix a possible double decref in _ctypes.c's PyCArrayType_new(). (GH-12530)
    5e33378

    @miss-islington
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    New changeset fa27870 by Miss Islington (bot) in branch '3.7':
    bpo-36421: Fix a possible double decref in _ctypes.c's PyCArrayType_new(). (GH-12530)
    fa27870

    @serhiy-storchaka
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    New changeset 0516f81 by Serhiy Storchaka (Zackery Spytz) in branch '2.7':
    [2.7] bpo-36421: Fix ref counting bugs in _ctypes.c's PyCArrayType_new(). (GH-12534)
    0516f81

    @vstinner
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    vstinner commented Jun 4, 2019

    just one question, how did you detect this bug?

    I bet that Zackery Spytz used Svace static analyzer: http://www.ispras.ru/en/technologies/svace/

    See also: https://python-security.readthedocs.io/security.html#static-analysers-of-cpython-code-base

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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