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gh-161407: Allocate audit hook entries with malloc() #161409

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gh-161407: Allocate audit hook entries with malloc() #161409

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18 changes: 18 additions & 0 deletions Lib/test/test_embed.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2062,6 +2062,24 @@ def test_open_code_hook(self):
def test_audit(self):
self.run_embedded_interpreter("test_audit")

def test_audit_hook_survives_allocator_change(self):

@vstinner vstinner Nov 6, 2026

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I don't think that adding a test is useful, since Python/sysmodule.c no longer depends on the Python memory allocator (PYTHONMALLOC) with this change. I suggest removing the test.

# A hook added before Py_Initialize() is freed at finalization, after
# PYTHONMALLOC changed the raw allocator: the entry must not be
# allocated with one allocator and freed with another.
allocators = ['debug']
if not support.Py_GIL_DISABLED:
allocators.append('malloc_debug')
if support.with_mimalloc():
allocators.extend(['mimalloc', 'mimalloc_debug'])
for allocator in allocators:
with self.subTest(allocator=allocator):
self.run_embedded_interpreter(
"test_audit", env={'PYTHONMALLOC': allocator})
# The development mode installs the debug hooks too
with self.subTest(dev_mode=True):
self.run_embedded_interpreter(
"test_audit", env={'PYTHONDEVMODE': '1'})

def test_audit_tuple(self):
self.run_embedded_interpreter("test_audit_tuple")

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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-11-05-10-51-17.gh-issue-161407.rVoqaQ.rst
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@@ -0,0 +1,3 @@
Fix a crash at exit when an audit hook was added with :c:func:`PySys_AddAuditHook`
before :c:func:`Py_Initialize` and the raw memory allocator changed during startup, for
example with ``PYTHONMALLOC=mimalloc`` or in the :ref:`Python Development Mode <devmode>`.
11 changes: 8 additions & 3 deletions Python/sysmodule.c
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Expand Up @@ -32,6 +32,7 @@ Data members:
#include "pycore_pylifecycle.h" // _PyErr_WriteUnraisableDefaultHook()
#include "pycore_pymath.h" // _PY_SHORT_FLOAT_REPR
#include "pycore_pymem.h" // _PyMem_DefaultRawFree()
#include "pycore_pymem_init.h" // _PyMem_RawMalloc()
#include "pycore_pystate.h" // _PyThreadState_GET()
#include "pycore_pystats.h" // _Py_PrintSpecializationStats()
#include "pycore_runtime.h" // _PyRuntimeState_Get*()
Expand Down Expand Up @@ -448,7 +449,7 @@ _PySys_ClearAuditHooks(PyThreadState *ts)
runtime->audit_hooks.head = NULL;
while (e) {
n = e->next;
PyMem_RawFree(e);
_PyMem_RawFree(NULL, e);
e = n;
}
}
Expand Down Expand Up @@ -496,8 +497,12 @@ PySys_AddAuditHook(Py_AuditHookFunction hook, void *userData)
}
}

_Py_AuditHookEntry *e = (_Py_AuditHookEntry*)PyMem_RawMalloc(
sizeof(_Py_AuditHookEntry));
/* Use malloc(), not PyMem_RawMalloc(): a hook can be added before

@vstinner vstinner Nov 6, 2026

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Honestly, I don't think that it's worth it to bother with _PyMem_RawMalloc() wrapper (and pass NULL as context). I would prefer to use malloc() / free() directly.

The "new" PyInitConfig C API also uses directly malloc() / free() to avoid troubles with changing the memory allocator.

Py_Initialize(), and the entry is freed during finalization, after
PYTHONMALLOC may have changed the raw allocator (and, in debug builds,
the allocator under the debug hooks). */
_Py_AuditHookEntry *e = (_Py_AuditHookEntry*)_PyMem_RawMalloc(
NULL, sizeof(_Py_AuditHookEntry));
if (!e) {
if (tstate != NULL) {
_PyErr_NoMemory(tstate);
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