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Parser hanging on stacked { tokens #90863

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tonybaloney mannequin opened this issue Feb 10, 2022 · 4 comments
Closed

Parser hanging on stacked { tokens #90863

tonybaloney mannequin opened this issue Feb 10, 2022 · 4 comments
Labels
3.10 only security fixes 3.11 only security fixes 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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@tonybaloney
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tonybaloney mannequin commented Feb 10, 2022

BPO 46707
Nosy @tonybaloney, @lysnikolaou, @pablogsal
PRs
  • bpo-46707: Avoid potential exponential backtracking in some syntax errors #31241
  • [3.10] bpo-46707: Avoid potential exponential backtracking in some syntax errors (GH-31241). #31242
    		•

    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 2022-02-10.03:54:55.013>
created_at = <Date 2022-02-10.03:00:43.493>
labels = ['interpreter-core', '3.10', 'type-crash', '3.11']
title = 'Parser hanging on stacked { tokens'
updated_at = <Date 2022-02-10.03:55:09.308>
user = 'https://github.com/tonybaloney'

    bugs.python.org fields:

    activity = <Date 2022-02-10.03:55:09.308>
actor = 'pablogsal'
assignee = 'none'
closed = True
closed_date = <Date 2022-02-10.03:54:55.013>
closer = 'pablogsal'
components = ['Parser']
creation = <Date 2022-02-10.03:00:43.493>
creator = 'anthonypjshaw'
dependencies = []
files = []
hgrepos = []
issue_num = 46707
keywords = ['patch', '3.10regression']
message_count = 4.0
messages = ['412972', '412974', '412975', '412976']
nosy_count = 3.0
nosy_names = ['anthonypjshaw', 'lys.nikolaou', 'pablogsal']
pr_nums = ['31241', '31242']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue46707'
versions = ['Python 3.10', 'Python 3.11']
    @tonybaloney
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    tonybaloney mannequin commented Feb 10, 2022

    Providing an (invalid) input to the parser causes an exponentially-slow DoS to the Python executable in 3.10.

    e.g.

    python3.10 -c "{{{{{{{{{{{{{{{{{{{{{:"

    takes ~2 seconds

    python3.10 -c "{{{{{{{{{{{{{{{{{{{{{{{{:"

    takes ~22 seconds

    Tested this all the way up to
    d{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{```{{{{{{{ef f():y

    which took over an hour

    @tonybaloney tonybaloney mannequin added interpreter-core (Objects, Python, Grammar, and Parser dirs) type-crash A hard crash of the interpreter, possibly with a core dump 3.10 only security fixes 3.11 only security fixes labels Feb 10, 2022
    @pablogsal
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    New changeset b71dc71 by Pablo Galindo Salgado in branch 'main':
    bpo-46707: Avoid potential exponential backtracking in some syntax errors (GH-31241)
    b71dc71

    @pablogsal
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    New changeset 9b23f8f by Pablo Galindo Salgado in branch '3.10':
    [3.10] bpo-46707: Avoid potential exponential backtracking in some syntax errors (GH-31241). (GH-31242)
    9b23f8f

    @pablogsal
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    Thanks Anthony for the report!

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
    @tonybaloney tonybaloney mentioned this issue Sep 20, 2022
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