bytearray().__buffer__(256) crashes

[sobolevn]

Crash report

Code says that it cannot fail:

cpython/Objects/bytearrayobject.c

Lines 44 to 56 in 4cd1076

	static int
	bytearray_getbuffer(PyObject *self, Py_buffer *view, int flags)
	{
	PyByteArrayObject *obj = _PyByteArray_CAST(self);
	if (view == NULL) {
	PyErr_SetString(PyExc_BufferError,
	"bytearray_getbuffer: view==NULL argument is obsolete");
	return -1;
	}
	void *ptr = (void *) PyByteArray_AS_STRING(obj);
	/* cannot fail if view != NULL and readonly == 0 */
	(void)PyBuffer_FillInfo(view, (PyObject*)obj, ptr, Py_SIZE(obj), 0, flags);

But, it can:

cpython/Objects/abstract.c

Lines 770 to 774 in 4cd1076

	if (flags != PyBUF_SIMPLE) { /* fast path */
	if (flags == PyBUF_READ || flags == PyBUF_WRITE) {
	PyErr_BadInternalCall();
	return -1;
	}

I have a PR ready.

CC @JelleZijlstra

Linked PRs

• gh-126980: Fix bytearray.__buffer__ crash on PyBUF_{READ,WRITE} #126981
• [3.13] gh-126980: Fix bytearray.__buffer__ crash on PyBUF_{READ,WRITE} (GH-126981) #127023