`PyDecContextObject` and `PyDecObject` in decimal module are missing `PyObject_GC_Track`

[CharlieZhao95]

Checklist

• I am confident this is a bug in CPython, not a bug in a third-party project
• I have searched the CPython issue tracker,
  and am confident this bug has not been reported before

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

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

No response

A clear and concise description of the bug:

There are two objects(PyDecContextObject and PyDecObject) using PyObject_GC_New in the decimal module, but PyObject_GC_Track is not added to their constructors.

PyDecContextObject:

cpython/Modules/_decimal/_decimal.c

Lines 1334 to 1380 in a794ebe

	static PyObject *
	context_new(PyTypeObject *type, PyObject *args UNUSED, PyObject *kwds UNUSED)
	{
	PyDecContextObject *self = NULL;
	mpd_context_t *ctx;
	decimal_state *state = get_module_state_by_def(type);
	if (type == state->PyDecContext_Type) {
	self = PyObject_GC_New(PyDecContextObject, state->PyDecContext_Type);
	}
	else {
	self = (PyDecContextObject *)type->tp_alloc(type, 0);
	}
	if (self == NULL) {
	return NULL;
	}
	self->traps = PyObject_CallObject((PyObject *)state->PyDecSignalDict_Type, NULL);
	if (self->traps == NULL) {
	self->flags = NULL;
	Py_DECREF(self);
	return NULL;
	}
	self->flags = PyObject_CallObject((PyObject *)state->PyDecSignalDict_Type, NULL);
	if (self->flags == NULL) {
	Py_DECREF(self);
	return NULL;
	}
	ctx = CTX(self);
	if (state->default_context_template) {
	*ctx = *CTX(state->default_context_template);
	}
	else {
	*ctx = dflt_ctx;
	}
	SdFlagAddr(self->traps) = &ctx->traps;
	SdFlagAddr(self->flags) = &ctx->status;
	CtxCaps(self) = 1;
	self->tstate = NULL;
	return (PyObject *)self;
	}

PyDecObject:

cpython/Modules/_decimal/_decimal.c

Lines 2002 to 2028 in a794ebe

	static PyObject *
	PyDecType_New(PyTypeObject *type)
	{
	PyDecObject *dec;
	decimal_state *state = get_module_state_by_def(type);
	if (type == state->PyDec_Type) {
	dec = PyObject_GC_New(PyDecObject, state->PyDec_Type);
	}
	else {
	dec = (PyDecObject *)type->tp_alloc(type, 0);
	}
	if (dec == NULL) {
	return NULL;
	}
	dec->hash = -1;
	MPD(dec)->flags = MPD_STATIC|MPD_STATIC_DATA;
	MPD(dec)->exp = 0;
	MPD(dec)->digits = 0;
	MPD(dec)->len = 0;
	MPD(dec)->alloc = _Py_DEC_MINALLOC;
	MPD(dec)->data = dec->data;
	return (PyObject *)dec;
	}

[CharlieZhao95]

Another problem is that when I tried to fix them, I added this code: CharlieZhao95@05cf606.

But there is a segfault when building, which seems to be a buff overflow error, what's wrong here?

Checked 106 modules (31 built-in, 74 shared, 1 n/a on linux-x86_64, 0 disabled, 0 missing, 0 failed on import)
Debug memory block at address p=0x7fcf053f5220: API '�'
    5786913340382969856 bytes originally requested
    The 7 pad bytes at p-7 are not all FORBIDDENBYTE (0xfd):
        at p-7: 0xdd *** OUCH
        at p-6: 0xdd *** OUCH
        at p-5: 0xdd *** OUCH
        at p-4: 0xdd *** OUCH
        at p-3: 0xdd *** OUCH
        at p-2: 0xdd *** OUCH
        at p-1: 0xdd *** OUCH
    Because memory is corrupted at the start, the count of bytes requested
       may be bogus, and checking the trailing pad bytes may segfault.
    The 8 pad bytes at tail=0x504fbed4d4be5220 are Segmentation fault (core dumped)