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base64.b32decode() leads into UnboundLocalError and OverflowError on some data #78345

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Barro mannequin opened this issue Jul 20, 2018 · 6 comments
Closed

base64.b32decode() leads into UnboundLocalError and OverflowError on some data #78345

Barro mannequin opened this issue Jul 20, 2018 · 6 comments
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3.7 (EOL) end of life 3.8 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@Barro
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Barro mannequin commented Jul 20, 2018

BPO 34164
Nosy @serhiy-storchaka, @Barro
PRs
  • bpo-34164: Fix handling of incorrect padding in base64.b32decode(). #8351
  • [3.7] bpo-34164: Fix handling of incorrect padding in base64.b32decode(). (GH-8351) #8435
  • [3.6] bpo-34164: Fix handling of incorrect padding in base64.b32decode(). (GH-8351) #8436
    		•

    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 2018-07-24.12:12:19.397>
created_at = <Date 2018-07-20.09:21:09.721>
labels = ['3.7', '3.8', 'type-bug', 'library']
title = 'base64.b32decode() leads into UnboundLocalError and OverflowError on some data'
updated_at = <Date 2018-07-24.12:12:19.396>
user = 'https://github.com/Barro'

    bugs.python.org fields:

    activity = <Date 2018-07-24.12:12:19.396>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2018-07-24.12:12:19.397>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2018-07-20.09:21:09.721>
creator = 'Barro'
dependencies = []
files = []
hgrepos = []
issue_num = 34164
keywords = ['patch']
message_count = 6.0
messages = ['321991', '321992', '322012', '322284', '322289', '322294']
nosy_count = 2.0
nosy_names = ['serhiy.storchaka', 'Barro']
pr_nums = ['8351', '8435', '8436']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue34164'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8']
    @Barro
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    Barro mannequin commented Jul 20, 2018

    base64.b32decode() function leads into "UnboundLocalError: local variable 'acc' referenced before assignment" when passing 8 equality signs as data:

    >>> import base64
>>> base64.b32decode(b"========")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/tmp/python-3.7-bin/lib/python3.7/base64.py", line 235, in b32decode
    acc <<= 5 * padchars
UnboundLocalError: local variable 'acc' referenced before assignment

    When passing a different number of equality signs, the documented binascii.Error exception is thrown.

    @Barro Barro mannequin added type-crash A hard crash of the interpreter, possibly with a core dump 3.7 (EOL) end of life stdlib Python modules in the Lib dir labels Jul 20, 2018
    @Barro
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    Barro mannequin commented Jul 20, 2018

    Apparently base64.b32decode() also has another issue that I missed when going through the issues with base64 module:

    >>> import base64
>>> base64.b32decode(b"M===============================")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/tmp/python-3.7-bin/lib/python3.7/base64.py", line 236, in b32decode
    last = acc.to_bytes(5, 'big')
OverflowError: int too big to convert

    @Barro Barro mannequin changed the title base64.b32decode() leads into UnboundLocalError on some data base64.b32decode() leads into UnboundLocalError and OverflowError on some data Jul 20, 2018
    @serhiy-storchaka
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    Thank you for your report Jussi.

    The type "crash" is used for hard crashes of the Python interpreter – possibly with a core dump or a Windows error box.

    @serhiy-storchaka serhiy-storchaka added 3.8 only security fixes type-bug An unexpected behavior, bug, or error and removed type-crash A hard crash of the interpreter, possibly with a core dump labels Jul 20, 2018
    @serhiy-storchaka
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    New changeset ac0b3c2 by Serhiy Storchaka in branch 'master':
    bpo-34164: Fix handling of incorrect padding in base64.b32decode(). (GH-8351)
    ac0b3c2

    @serhiy-storchaka
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    New changeset 0b27169 by Serhiy Storchaka (Miss Islington (bot)) in branch '3.7':
    bpo-34164: Fix handling of incorrect padding in base64.b32decode(). (GH-8351) (GH-8435)
    0b27169

    @serhiy-storchaka
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    New changeset 113f86e by Serhiy Storchaka in branch '3.6':
    [3.6] bpo-34164: Fix handling of incorrect padding in base64.b32decode(). (GH-8351) (GH-8436)
    113f86e

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