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bpo-31752: Fix possible crash in timedelta constructor called with cu…

…stom integers. (GH-3947) (#4086)

Bad remainder in divmod() in intermediate calculations caused an assertion failure.
(cherry picked from commit 4ffd465)
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miss-islington authored and serhiy-storchaka committed Oct 23, 2017
1 parent aaf6a3d commit 6e45d7b90accbbdfef353c41ab0a78a3e4742803
@@ -866,6 +866,26 @@ def as_integer_ratio(self):
with self.assertRaises(ValueError):
timedelta() * get_bad_float(bad_ratio)

def test_issue31752(self):
# The interpreter shouldn't crash because divmod() returns negative
# remainder.
class BadInt(int):
def __mul__(self, other):
return Prod()

class Prod:
def __radd__(self, other):
return Sum()

class Sum(int):
def __divmod__(self, other):
# negative remainder
return (0, -1)

timedelta(microseconds=BadInt(1))
timedelta(hours=BadInt(1))
timedelta(weeks=BadInt(1))


#############################################################################
# date tests
@@ -0,0 +1 @@
Fix possible crash in timedelta constructor called with custom integers.
@@ -1533,6 +1533,7 @@ delta_to_microseconds(PyDateTime_Delta *self)
if (x2 == NULL)
goto Done;
result = PyNumber_Add(x1, x2);
assert(result == NULL || PyLong_CheckExact(result));

Done:
Py_XDECREF(x1);
@@ -1555,6 +1556,7 @@ microseconds_to_delta_ex(PyObject *pyus, PyTypeObject *type)
PyObject *num = NULL;
PyObject *result = NULL;

assert(PyLong_CheckExact(pyus));
tuple = PyNumber_Divmod(pyus, us_per_second);
if (tuple == NULL)
goto Done;
@@ -2108,11 +2110,13 @@ accum(const char* tag, PyObject *sofar, PyObject *num, PyObject *factor,
assert(num != NULL);

if (PyLong_Check(num)) {
prod = PyNumber_Multiply(num, factor);
prod = PyNumber_Multiply(factor, num);
if (prod == NULL)
return NULL;
assert(PyLong_CheckExact(prod));
sum = PyNumber_Add(sofar, prod);
Py_DECREF(prod);
assert(sum == NULL || PyLong_CheckExact(sum));
return sum;
}

@@ -2155,7 +2159,7 @@ accum(const char* tag, PyObject *sofar, PyObject *num, PyObject *factor,
* fractional part requires float arithmetic, and may
* lose a little info.
*/
assert(PyLong_Check(factor));
assert(PyLong_CheckExact(factor));
dnum = PyLong_AsDouble(factor);

dnum *= fracpart;
@@ -2170,6 +2174,7 @@ accum(const char* tag, PyObject *sofar, PyObject *num, PyObject *factor,
Py_DECREF(sum);
Py_DECREF(x);
*leftover += fracpart;
assert(y == NULL || PyLong_CheckExact(y));
return y;
}

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