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Patch #1462488: prevent a segfault in object_reduce_ex() by splitting

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the implementation for __reduce__ and __reduce_ex__ into two separate
functions. Fixes bug #931877.
 (backport from rev. 54397)
This commit is contained in:
Žiga Seilnacht 2007-03-15 11:47:59 +00:00
parent 7cd6ef0913
commit c1b4e8e6e2
3 changed files with 82 additions and 14 deletions
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61
Objects/typeobject.c
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@ -2708,11 +2708,54 @@ reduce_2(PyObject *obj)
return res;
}
/*
* There were two problems when object.__reduce__ and object.__reduce_ex__
* were implemented in the same function:
* - trying to pickle an object with a custom __reduce__ method that
* fell back to object.__reduce__ in certain circumstances led to
* infinite recursion at Python level and eventual RuntimeError.
* - Pickling objects that lied about their type by overwriting the
* __class__ descriptor could lead to infinite recursion at C level
* and eventual segfault.
*
* Because of backwards compatibility, the two methods still have to
* behave in the same way, even if this is not required by the pickle
* protocol. This common functionality was moved to the _common_reduce
* function.
*/
static PyObject *
_common_reduce(PyObject *self, int proto)
{
PyObject *copy_reg, *res;
if (proto >= 2)
return reduce_2(self);
copy_reg = import_copy_reg();
if (!copy_reg)
return NULL;
res = PyEval_CallMethod(copy_reg, "_reduce_ex", "(Oi)", self, proto);
Py_DECREF(copy_reg);
return res;
}
static PyObject *
object_reduce(PyObject *self, PyObject *args)
{
int proto = 0;
if (!PyArg_ParseTuple(args, "|i:__reduce__", &proto))
return NULL;
return _common_reduce(self, proto);
}
static PyObject *
object_reduce_ex(PyObject *self, PyObject *args)
{
/* Call copy_reg._reduce_ex(self, proto) */
PyObject *reduce, *copy_reg, *res;
PyObject *reduce, *res;
int proto = 0;
if (!PyArg_ParseTuple(args, "|i:__reduce_ex__", &proto))
@ -2748,23 +2791,13 @@ object_reduce_ex(PyObject *self, PyObject *args)
Py_DECREF(reduce);
}
if (proto >= 2)
return reduce_2(self);
copy_reg = import_copy_reg();
if (!copy_reg)
return NULL;
res = PyEval_CallMethod(copy_reg, "_reduce_ex", "(Oi)", self, proto);
Py_DECREF(copy_reg);
return res;
return _common_reduce(self, proto);
}
static PyMethodDef object_methods[] = {
{"__reduce_ex__", object_reduce_ex, METH_VARARGS,
PyDoc_STR("helper for pickle")},
{"__reduce__", object_reduce_ex, METH_VARARGS,
{"__reduce__", object_reduce, METH_VARARGS,
PyDoc_STR("helper for pickle")},
{0}
};