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Double deallocation on iterator exhausting #70681

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serhiy-storchaka opened this issue Mar 6, 2016 · 8 comments
Closed

Double deallocation on iterator exhausting #70681

serhiy-storchaka opened this issue Mar 6, 2016 · 8 comments
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@serhiy-storchaka
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interpreter-core (Objects, Python, Grammar, and Parser dirs) type-crash A hard crash of the interpreter, possibly with a core dump

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@serhiy-storchaka
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BPO 26494
Nosy @rhettinger, @serhiy-storchaka
Files
  • free_after_iterating.patch
  • free_after_iterating_2.patch
  • free_after_iterating_3.patch
    		•

    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 = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2016-03-31.12:17:47.383>
created_at = <Date 2016-03-06.18:26:04.911>
labels = ['interpreter-core', 'type-crash']
title = 'Double deallocation on iterator exhausting'
updated_at = <Date 2016-03-31.12:17:47.382>
user = 'https://github.com/serhiy-storchaka'

    bugs.python.org fields:

    activity = <Date 2016-03-31.12:17:47.382>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2016-03-31.12:17:47.383>
closer = 'serhiy.storchaka'
components = ['Interpreter Core']
creation = <Date 2016-03-06.18:26:04.911>
creator = 'serhiy.storchaka'
dependencies = []
files = ['42080', '42081', '42092']
hgrepos = []
issue_num = 26494
keywords = ['patch']
message_count = 8.0
messages = ['261263', '261270', '261343', '261348', '261420', '261426', '261734', '262675']
nosy_count = 4.0
nosy_names = ['rhettinger', 'python-dev', 'serhiy.storchaka', 'scorp']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue26494'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6']
    @serhiy-storchaka
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    Following example causes double deallocation of a sequence and crashing.

    class A(list):
    def __del__(self):
        next(it)

it = iter(A())
next(it)

    The same is for subclass of tuple, str, bytes and bytearray.

    Proposed patch fixes this issue.

    @serhiy-storchaka serhiy-storchaka added interpreter-core (Objects, Python, Grammar, and Parser dirs) type-crash A hard crash of the interpreter, possibly with a core dump labels Mar 6, 2016
    @serhiy-storchaka
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    Updated patch fixes also set, dict and os.scandir() iterator.

    May be sqlite3 cursor needs a fix, but it is too complicated.

    @serhiy-storchaka
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    TODO: After resolving bpo-26492 add the test for array.

    @serhiy-storchaka
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    Fixed test for OrderedDict. Tests for list and tuple are moved up to seq_tests.py.

    @scorp
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    Mannequin

    scorp mannequin commented Mar 9, 2016

    Hi Serhiy,

    I tried the short example you gave, but it doesn't crash. I'm getting:

    Exception ignored in: <bound method A.__del__ of []>
Traceback (most recent call last):
  File "./test.py", line 5, in __del__
    next(it)
StopIteration
Exception ignored in: <bound method A.__del__ of []>
Traceback (most recent call last):
  File "./test.py", line 5, in __del__
    next(it)
StopIteration
Traceback (most recent call last):
  File "./test.py", line 8, in <module>
    next(it)
StopIteration

    Am I missing something?

    @serhiy-storchaka
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    It crashes in debug build.

    @serhiy-storchaka
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    Could anyone please look at the patch? I'm not sure about organizing tests.

    @python-dev
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    python-dev mannequin commented Mar 30, 2016

    New changeset 905b5944119c by Serhiy Storchaka in branch '3.5':
    Issue bpo-26494: Fixed crash on iterating exhausting iterators.
    https://hg.python.org/cpython/rev/905b5944119c

    New changeset 73ce47d4a7b2 by Serhiy Storchaka in branch 'default':
    Issue bpo-26494: Fixed crash on iterating exhausting iterators.
    https://hg.python.org/cpython/rev/73ce47d4a7b2

    New changeset cff06d875678 by Serhiy Storchaka in branch '2.7':
    Issue bpo-26494: Fixed crash on iterating exhausting iterators.
    https://hg.python.org/cpython/rev/cff06d875678

    @serhiy-storchaka serhiy-storchaka self-assigned this Mar 31, 2016
    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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