`configparser.RawConfigParser.{OPTCRE,OPTCRE_NV}` regexes vulnerable to quadratic backtracking

[StanFromIreland]

Bug report

Bug description:

Found by OSS Fuzz in #461069020.

The below reproducer:

import configparser
import time

for N in (10000, 20000, 30000, 40000):
 cfg = (
 "[section]" +
 "\n" + "x" + " " * N + "y" + "\n"
 )
 parser = configparser.RawConfigParser()
 s = time.perf_counter()
 try: parser.read_string(cfg)
 except: pass
 t = time.perf_counter() - s
 print(f"{N} {t}")

reveals the quadratic behaviour:

10000 0.5478692570177373
20000 2.175520057004178
30000 4.97204191898345
40000 8.673784376995172

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-146333: Fix quadratic regex backtracking in configparser option parsing #146399
• [3.14] gh-146333: Fix quadratic regex backtracking in configparser option parsing (GH-146399) #148287
• [3.13] gh-146333: Fix quadratic regex backtracking in configparser option parsing (GH-146399) #148559
• [3.12] gh-146333: Fix quadratic regex backtracking in configparser option parsing (GH-146399) (GH-148559) #154081
• [3.11] gh-146333: Fix quadratic regex backtracking in configparser option parsing (GH-146399) (GH-148559) #154877
• [3.10] gh-146333: Fix quadratic regex backtracking in configparser option parsing (GH-146399) (GH-148559) #154878
• [3.11] gh-146333: Fix quadratic regex backtracking in configparser option parsing (GH-146399) (GH-148559) (GH-154081) #155160
• [3.10] gh-146333: Fix quadratic regex backtracking in configparser option parsing (GH-146399) (GH-148559) (GH-154081) #155161