syslogmodule.c lack of NULL check

[wooffie]

Bug description:

cpython/Modules/syslogmodule.c

Line 178 in 7ec1742

if (PySys_Audit("syslog.openlog", "Oll", ident ? ident : Py_None, logopt, facility) < 0) {

After in if body we use Py_DECREF(indent), which can cause null pointer dereference

CPython versions tested on:

CPython main branch

Operating systems tested on:

Other

Additional information

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Reporter: Burkov Egor (eburkov@rvision.ru).

Organization: R-Vision (support@rvision.ru).

Linked PRs

• gh-129345: null check for indent syslogmodule #129348
• [3.13] gh-129345: null check for indent syslogmodule (GH-129348) #129442
• [3.12] gh-129345: null check for indent syslogmodule (GH-129348) #129443

[serhiy-storchaka]

Do you want to provide a PR?

[wooffie]

Do you want to provide a PR?

yes, sure

[ZeroIntensity]

Quick reproducer for a test case:

import syslog
import sys

sys.argv = None
def audit(event, _):
    if event == "syslog.openlog":
        raise RuntimeError("I didn't expect the spanish inquisition")

sys.addaudithook(audit)
syslog.openlog()