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Segfault from new PEG parser handling yield withing f-strings #85081

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stestagg mannequin opened this issue Jun 7, 2020 · 4 comments
Closed

Segfault from new PEG parser handling yield withing f-strings #85081

stestagg mannequin opened this issue Jun 7, 2020 · 4 comments
Labels
3.9 only security fixes 3.10 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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@stestagg
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stestagg mannequin commented Jun 7, 2020

BPO 40904
Nosy @gvanrossum, @lysnikolaou, @pablogsal, @miss-islington, @stestagg
PRs
  • bpo-40904: Fix segfault in the new parser with f-string containing yield statements with no value #20701
  • [3.9] bpo-40904: Fix segfault in the new parser with f-string containing yield statements with no value (GH-20701) #20702
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    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 2020-06-08.00:48:33.792>
created_at = <Date 2020-06-07.23:06:21.114>
labels = ['interpreter-core', '3.10', '3.9', 'type-crash']
title = 'Segfault from new PEG parser handling yield withing f-strings'
updated_at = <Date 2020-06-08.01:08:56.576>
user = 'https://github.com/stestagg'

    bugs.python.org fields:

    activity = <Date 2020-06-08.01:08:56.576>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2020-06-08.00:48:33.792>
closer = 'pablogsal'
components = ['Interpreter Core']
creation = <Date 2020-06-07.23:06:21.114>
creator = 'stestagg'
dependencies = []
files = []
hgrepos = []
issue_num = 40904
keywords = ['patch', '3.9regression']
message_count = 4.0
messages = ['370923', '370942', '370943', '370946']
nosy_count = 5.0
nosy_names = ['gvanrossum', 'lys.nikolaou', 'pablogsal', 'miss-islington', 'stestagg']
pr_nums = ['20701', '20702']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue40904'
versions = ['Python 3.9', 'Python 3.10']
    @stestagg
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    stestagg mannequin commented Jun 7, 2020

    The following command causes python to segfault:

    $ echo "f'{yield}'" | python/bin/python3

    Bisect tracked this down to:

    c5fc156 (bpo-40334: PEP-617 implementation: New PEG parser for CPython (GH-19503))

    The illegal access is coming out of fstring_shift_children_locations
    as n->v.Yield.value is None.

    Correspondingly, the following produces the expected output:

    $ echo "f'{yield 1}'" | python/bin/python3

    Suggesting there's a missing check for no yield value in this code.

    @stestagg stestagg mannequin added 3.10 only security fixes interpreter-core (Objects, Python, Grammar, and Parser dirs) type-crash A hard crash of the interpreter, possibly with a core dump labels Jun 7, 2020
    @vstinner vstinner added 3.9 only security fixes labels Jun 7, 2020
    @pablogsal
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    New changeset 972ab03 by Pablo Galindo in branch 'master':
    bpo-40904: Fix segfault in the new parser with f-string containing yield statements with no value (GH-20701)
    972ab03

    @pablogsal
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    Thanks, Steve for the report!

    @miss-islington
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    New changeset 6440911 by Miss Islington (bot) in branch '3.9':
    bpo-40904: Fix segfault in the new parser with f-string containing yield statements with no value (GH-20701)
    6440911

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