[issue39276] type() cause segmentation fault in callback function called from C extension

[Irit Katriel]

Change by Irit Katriel :


--
resolution:  -> not a bug
stage:  -> resolved
status: open -> closed

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[issue39276] type() cause segmentation fault in callback function called from C extension

[Giacomo Mazzamuto]

Giacomo Mazzamuto  added the comment:

Hello,

the segmentation fault is also resolved by finalizing the initialization of 
InternalType by calling PyType_Ready(), just like you do with 
ExternalType

--
nosy: +Giacomo Mazzamuto

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[issue39276] type() cause segmentation fault in callback function called from C extension

[Pablo Galindo Salgado]

Change by Pablo Galindo Salgado :


--
Removed message: https://bugs.python.org/msg359687

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[issue39276] type() cause segmentation fault in callback function called from C extension

[Pablo Galindo Salgado]

Pablo Galindo Salgado  added the comment:

static PyTypeObject InternalType should have

PyVarObject_HEAD_INIT(_Type, 0) 

instead of

PyVarObject_HEAD_INIT(NULL, 0)

--
nosy: +pablogsal

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[issue39276] type() cause segmentation fault in callback function called from C extension

[Paweł Karczewski]

New submission from Paweł Karczewski :

How to reproduce:

1. Create callback function, which may take any object and run type() on it
  def builtin_type_in_callback(obj):
  type(obj)

2. Create C extension with two types defined in it - Internal and External. 
  Eternal type should implement method (let's name it Call), which can get 
callback function

static PyObject *
Call(ExternalObject *self, PyObject* args) {
PyObject* python_callback;
if (!PyArg_ParseTuple(args, "O:set_callback",  
_callback)) {
return NULL;
}
callback_runner(python_callback);
if(PyErr_Occurred() != NULL)
return NULL;
Py_RETURN_NONE;
}  
  Inside this function create object of Internal type and pass it to callback 
function
void callback_runner(void* callback_function)  {
InternalObject *entry = PyObject_New(InternalObject, 
);
PyObject_Init((PyObject*)entry, );
PyObject *args = PyTuple_New(1);
if (args != NULL) {
if (PyTuple_SetItem(args, 0, (PyObject *)entry) == 0) {
PyObject *res = PyObject_CallObject((PyObject 
*) callback_function, args);
Py_XDECREF(res);
}
}

When type() is called on object of Internal type segmentation fault occur. 
However, if dir() was called
on such object before type(), type() works properly and returns type of 
Internal Object.

For more details please look into reproducer code.

--
components: C API
files: cpython_type_segfaulter.tgz
messages: 359680
nosy: karczex
priority: normal
severity: normal
status: open
title: type() cause segmentation fault  in callback function called from C 
extension
versions: Python 3.7, Python 3.8
Added file: https://bugs.python.org/file48834/cpython_type_segfaulter.tgz

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