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gh-131311: Fix memory leak in PyCStructUnionType_update_stginfo #131312

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Merged
merged 2 commits into from
Mar 18, 2025
Merged

gh-131311: Fix memory leak in PyCStructUnionType_update_stginfo #131312

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a4f8468
Fix memory leak in PyCStructUnionType_update_stginfo
sergey-miryanov Mar 15, 2025
d978ab5
Move cleanup of locals to error section
sergey-miryanov Mar 17, 2025
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40 changes: 24 additions & 16 deletions Modules/_ctypes/stgdict.c
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Original file line number Diff line number Diff line change
Expand Up @@ -217,13 +217,17 @@ MakeAnonFields(PyObject *type)
int
PyCStructUnionType_update_stginfo(PyObject *type, PyObject *fields, int isStruct)
{
PyObject *tmp;
Py_ssize_t ffi_ofs;
int arrays_seen = 0;

int retval = -1;
// The following are NULL or hold strong references.
// They're cleared on error.
PyObject *layout_func = NULL;
PyObject *kwnames = NULL;
PyObject* align = NULL;
PyObject* size = NULL;
PyObject *layout_fields_obj = NULL;
PyObject *layout_fields = NULL;
PyObject *layout = NULL;
PyObject *format_spec_obj = NULL;
Expand Down Expand Up @@ -257,12 +261,11 @@ PyCStructUnionType_update_stginfo(PyObject *type, PyObject *fields, int isStruct
goto error;
}

PyObject *layout_func = PyImport_ImportModuleAttrString("ctypes._layout",
"get_layout");
layout_func = PyImport_ImportModuleAttrString("ctypes._layout", "get_layout");
if (!layout_func) {
goto error;
}
PyObject *kwnames = PyTuple_Pack(
kwnames = PyTuple_Pack(
2,
&_Py_ID(is_struct),
&_Py_ID(base));
Expand All @@ -281,19 +284,19 @@ PyCStructUnionType_update_stginfo(PyObject *type, PyObject *fields, int isStruct
baseinfo ? base : Py_None},
2 | PY_VECTORCALL_ARGUMENTS_OFFSET,
kwnames);
Py_DECREF(kwnames);
Py_DECREF(layout_func);
Py_CLEAR(kwnames);
Py_CLEAR(layout_func);
fields = NULL; // a borrowed reference we won't be using again
if (!layout) {
goto error;
}

tmp = PyObject_GetAttr(layout, &_Py_ID(align));
if (!tmp) {
align = PyObject_GetAttr(layout, &_Py_ID(align));
if (!align) {
goto error;
}
Py_ssize_t total_align = PyLong_AsSsize_t(tmp);
Py_DECREF(tmp);
Py_ssize_t total_align = PyLong_AsSsize_t(align);
Py_CLEAR(align);
if (total_align < 0) {
if (!PyErr_Occurred()) {
PyErr_SetString(PyExc_ValueError,
Expand All @@ -302,12 +305,12 @@ PyCStructUnionType_update_stginfo(PyObject *type, PyObject *fields, int isStruct
goto error;
}

tmp = PyObject_GetAttr(layout, &_Py_ID(size));
if (!tmp) {
size = PyObject_GetAttr(layout, &_Py_ID(size));
if (!size) {
goto error;
}
Py_ssize_t total_size = PyLong_AsSsize_t(tmp);
Py_DECREF(tmp);
Py_ssize_t total_size = PyLong_AsSsize_t(size);
Py_CLEAR(size);
if (total_size < 0) {
if (!PyErr_Occurred()) {
PyErr_SetString(PyExc_ValueError,
Expand Down Expand Up @@ -338,15 +341,15 @@ PyCStructUnionType_update_stginfo(PyObject *type, PyObject *fields, int isStruct
}
memcpy(stginfo->format, format_spec, format_spec_size + 1);

PyObject *layout_fields_obj = PyObject_GetAttr(layout, &_Py_ID(fields));
layout_fields_obj = PyObject_GetAttr(layout, &_Py_ID(fields));
if (!layout_fields_obj) {
goto error;
}
layout_fields = PySequence_Tuple(layout_fields_obj);
Py_DECREF(layout_fields_obj);
if (!layout_fields) {
goto error;
}
Py_CLEAR(layout_fields_obj);
Py_CLEAR(layout);

Py_ssize_t len = PyTuple_GET_SIZE(layout_fields);
Expand Down Expand Up @@ -664,6 +667,11 @@ PyCStructUnionType_update_stginfo(PyObject *type, PyObject *fields, int isStruct

retval = MakeAnonFields(type);
error:
Py_XDECREF(layout_func);
Py_XDECREF(kwnames);
Py_XDECREF(align);
Py_XDECREF(size);
Py_XDECREF(layout_fields_obj);
Py_XDECREF(layout_fields);
Py_XDECREF(layout);
Py_XDECREF(format_spec_obj);
Expand Down
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