OverflowError with SafeLoader found via fuzzing

[gvozdila]

Hi! I'v found crash with OverflowError.

Way to reproduce

#!/usr/bin/python3

import yaml
import sys

with open(sys.argv[1], 'r', encoding="utf-8",errors='ignore') as inp_file:
    test_string = inp_file.read()
    yaml.safe_load(test_string)

Error message:

$ python3 test.py ./crash-test.txt
Traceback (most recent call last):
File "/root/test.py", line 8, in
yaml.safe_load(test_string)
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/init.py", line 125, in safe_load
return load(stream, SafeLoader)
^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/init.py", line 81, in load
return loader.get_single_data()
^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/constructor.py", line 49, in get_single_data
node = self.get_single_node()
^^^^^^^^^^^^^^^^^^^^^^
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/composer.py", line 35, in get_single_node
if not self.check_event(StreamEndEvent):
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/parser.py", line 98, in check_event
self.current_event = self.state()
^^^^^^^^^^^^
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/parser.py", line 142, in parse_implicit_document_start
if not self.check_token(DirectiveToken, DocumentStartToken,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/scanner.py", line 116, in check_token
self.fetch_more_tokens()
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/scanner.py", line 251, in fetch_more_tokens
return self.fetch_double()
^^^^^^^^^^^^^^^^^^^
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/scanner.py", line 655, in fetch_double
self.fetch_flow_scalar(style='"')
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/scanner.py", line 666, in fetch_flow_scalar
self.tokens.append(self.scan_flow_scalar(style))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/scanner.py", line 1149, in scan_flow_scalar
chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/ttt/lib/python3.11/site-packages/PyYAML-7.0.0.dev0-py3.11-linux-x86_64.egg/yaml/scanner.py", line 1217, in scan_flow_scalar_non_spaces
chunks.append(chr(code))
^^^^^^^^^
OverflowError: Python int too large to convert to C int

On some configs error "OverflowError: signed integer is greater than maximum"

Crash present at least from v6.0, appears with and without libyaml.

There is a patch in cpython fixing OverflowError to ValueError.
python/cpython@e2c4038

crash-test.txt