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| author | Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> | 2024-06-17 19:12:25 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-06-17 19:12:25 (GMT) |
| commit | 396f8b0b98441344e1d3223a4075e5e342e0c2df (patch) | |
| tree | 0d223474986d5d3054de64bfb8c36a340d1243e8 /Python/structmember.c | |
| parent | 0dbb86c5bebf8d85dd295840261e1c944726271c (diff) | |
| download | cpython-396f8b0b98441344e1d3223a4075e5e342e0c2df.zip cpython-396f8b0b98441344e1d3223a4075e5e342e0c2df.tar.gz cpython-396f8b0b98441344e1d3223a4075e5e342e0c2df.tar.bz2 | |
[3.13] gh-117657: Fix `__slots__` thread safety in free-threaded build (GH-119368) (#120655)
Fix a race in `PyMember_GetOne` and `PyMember_SetOne` for `Py_T_OBJECT_EX`.
These functions implement `__slots__` accesses for Python objects.
(cherry picked from commit 362cd2680b45a36c3467b9721ff7fc0ceb338452)
Co-authored-by: Daniele Parmeggiani <8658291+dpdani@users.noreply.github.com>
Diffstat (limited to 'Python/structmember.c')
| -rw-r--r-- | Python/structmember.c | 42 |
1 files changed, 33 insertions, 9 deletions
diff --git a/Python/structmember.c b/Python/structmember.c index ba881d1..d5e7ab8 100644 --- a/Python/structmember.c +++ b/Python/structmember.c @@ -4,8 +4,22 @@ #include "Python.h" #include "pycore_abstract.h" // _PyNumber_Index() #include "pycore_long.h" // _PyLong_IsNegative() +#include "pycore_object.h" // _Py_TryIncrefCompare(), FT_ATOMIC_*() +#include "pycore_critical_section.h" +static inline PyObject * +member_get_object(const char *addr, const char *obj_addr, PyMemberDef *l) +{ + PyObject *v = FT_ATOMIC_LOAD_PTR(*(PyObject **) addr); + if (v == NULL) { + PyErr_Format(PyExc_AttributeError, + "'%T' object has no attribute '%s'", + (PyObject *)obj_addr, l->name); + } + return v; +} + PyObject * PyMember_GetOne(const char *obj_addr, PyMemberDef *l) { @@ -75,15 +89,19 @@ PyMember_GetOne(const char *obj_addr, PyMemberDef *l) Py_INCREF(v); break; case Py_T_OBJECT_EX: - v = *(PyObject **)addr; - if (v == NULL) { - PyObject *obj = (PyObject *)obj_addr; - PyTypeObject *tp = Py_TYPE(obj); - PyErr_Format(PyExc_AttributeError, - "'%.200s' object has no attribute '%s'", - tp->tp_name, l->name); - } + v = member_get_object(addr, obj_addr, l); +#ifndef Py_GIL_DISABLED Py_XINCREF(v); +#else + if (v != NULL) { + if (!_Py_TryIncrefCompare((PyObject **) addr, v)) { + Py_BEGIN_CRITICAL_SECTION((PyObject *) obj_addr); + v = member_get_object(addr, obj_addr, l); + Py_XINCREF(v); + Py_END_CRITICAL_SECTION(); + } + } +#endif break; case Py_T_LONGLONG: v = PyLong_FromLongLong(*(long long *)addr); @@ -92,6 +110,7 @@ PyMember_GetOne(const char *obj_addr, PyMemberDef *l) v = PyLong_FromUnsignedLongLong(*(unsigned long long *)addr); break; case _Py_T_NONE: + // doesn't require free-threading code path v = Py_NewRef(Py_None); break; default: @@ -118,6 +137,9 @@ PyMember_SetOne(char *addr, PyMemberDef *l, PyObject *v) return -1; } +#ifdef Py_GIL_DISABLED + PyObject *obj = (PyObject *) addr; +#endif addr += l->offset; if ((l->flags & Py_READONLY)) @@ -281,8 +303,10 @@ PyMember_SetOne(char *addr, PyMemberDef *l, PyObject *v) break; case _Py_T_OBJECT: case Py_T_OBJECT_EX: + Py_BEGIN_CRITICAL_SECTION(obj); oldv = *(PyObject **)addr; - *(PyObject **)addr = Py_XNewRef(v); + FT_ATOMIC_STORE_PTR_RELEASE(*(PyObject **)addr, Py_XNewRef(v)); + Py_END_CRITICAL_SECTION(); Py_XDECREF(oldv); break; case Py_T_CHAR: { |