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

pablogsal · 2020-09-02T16:52:26Z

…

This program can segfault the parser by stack overflow:

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 }] {
[...] }.
(cherry picked from commit 4a97b15)

Co-authored-by: Pablo Galindo [email protected]

https://bugs.python.org/issue41690

…recursion (pythonGH-22053) This program can segfault the parser by stack overflow: ``` 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 }] { [...] }. (cherry picked from commit 4a97b15) Co-authored-by: Pablo Galindo <[email protected]>

pablogsal requested a review from lysnikolaou as a code owner September 2, 2020 16:52

the-knights-who-say-ni added the CLA signed label Sep 2, 2020

bedevere-bot mentioned this pull request Sep 2, 2020

bpo-41690: Use a loop to collect args in the parser instead of recursion #22053

Merged

bedevere-bot added the awaiting core review label Sep 2, 2020

pablogsal merged commit 8de34cd into python:3.9 Sep 2, 2020

bedevere-bot removed the awaiting core review label Sep 2, 2020

pablogsal deleted the backport-4a97b15-3.9 branch May 19, 2021 18:58

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