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Use a loop to collect args in the parser instead of recursion #85856

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pablogsal opened this issue Sep 2, 2020 · 3 comments
Closed

Use a loop to collect args in the parser instead of recursion #85856

pablogsal opened this issue Sep 2, 2020 · 3 comments
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3.9 only security fixes 3.10 only security fixes

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@pablogsal
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BPO 41690
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  • bpo-41690: Use a loop to collect args in the parser instead of recursion #22053
  • [3.9] bpo-41690: Use a loop to collect args in the parser instead of recursion (GH-22053) #22067
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    GitHub fields:

    assignee = None
closed_at = <Date 2020-09-02.20:31:14.576>
created_at = <Date 2020-09-02.10:59:21.311>
labels = ['3.9', '3.10']
title = 'Use a loop to collect args in the parser instead of recursion'
updated_at = <Date 2020-09-02.20:31:14.576>
user = 'https://github.com/pablogsal'

    bugs.python.org fields:

    activity = <Date 2020-09-02.20:31:14.576>
actor = 'pablogsal'
assignee = 'none'
closed = True
closed_date = <Date 2020-09-02.20:31:14.576>
closer = 'pablogsal'
components = []
creation = <Date 2020-09-02.10:59:21.311>
creator = 'pablogsal'
dependencies = []
files = []
hgrepos = []
issue_num = 41690
keywords = ['patch']
message_count = 3.0
messages = ['376225', '376255', '376263']
nosy_count = 1.0
nosy_names = ['pablogsal']
pr_nums = ['22053', '22067']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue41690'
versions = ['Python 3.9', 'Python 3.10']
    @pablogsal
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    This program can segfault the parser by stackoverflow:

    import ast

code = "f(" + ",".join(['a' for _ in range(100000)]) + ")"
print("Ready!")
ast.parse(code)

    the reason is that the rule for arguments has a simple recursion when collecting args:

    args[expr_ty]:
    [...]
    | a=named_expression b=[',' c=args { c }] {
    [...] }

    Check https://github.com/we-like-parsers/pegen/issues/245 for more context and informaton

    @pablogsal pablogsal added 3.9 only security fixes 3.10 only security fixes labels Sep 2, 2020
    @pablogsal
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    New changeset 4a97b15 by Pablo Galindo in branch 'master':
    bpo-41690: Use a loop to collect args in the parser instead of recursion (GH-22053)
    4a97b15

    @pablogsal
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    New changeset 8de34cd by Pablo Galindo in branch '3.9':
    [3.9] bpo-41690: Use a loop to collect args in the parser instead of recursion (GH-22053) (GH-22067)
    8de34cd

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