ExtensionFileLoader.load_module aborts when initialized with a path containing null-bytes

[devdanzin]

Crash report

What happened?

It's possible to abort a debug build by initializing a _frozen_importlib_external.ExtensionFileLoader with a path containing null-bytes, then calling load_module():

import _frozen_importlib_external

_frozen_importlib_external.ExtensionFileLoader("a", "\x00").load_module(None)

Abort message:

python: Python/import.c:939: hashtable_key_from_2_strings: Assertion `strlen(key) == size - 1' failed.
Aborted

Found using fusil by @vstinner.

CPython versions tested on:

3.12, 3.13, 3.14, CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.14.0a2+ (heads/main:0af4ec3, Nov 20 2024, 21:45:19) [GCC 13.2.0]

Linked PRs

• gh-127208: Reject null character in _imp.create_dynamic() #127400
• [3.13] gh-127208: Reject null character in _imp.create_dynamic() (GH-127400) #127418
• [3.12] gh-127208: Reject null character in _imp.create_dynamic() (#127400) #127419

[devdanzin]

Another way to trigger:

>>> import _imp
>>> class n:
...   name = "A"
...   origin = "\x00"
...
>>> _imp.create_dynamic(n, 1)
python: Python/import.c:939: hashtable_key_from_2_strings: Assertion `strlen(key) == size - 1' failed.
Aborted

[vstinner]

I wrote #127400 to fix the issue.

[picnixz]

Closing since completed and backported.