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authorStefan Krah <skrah@bytereef.org>2016-07-17 12:01:42 (GMT)
committerStefan Krah <skrah@bytereef.org>2016-07-17 12:01:42 (GMT)
commit8c126f17f09eeb75d3d3c9737150384cd1dd9c03 (patch)
treedeb229d3647b9950ffb59999ebc2fe0ddba772c7
parent80ab069f1b040b7418833d9c1facf77ad2bd4363 (diff)
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Issue #26974: Fix segfault in the presence of absurd subclassing. Proactively
eliminate all internal uses of overridden methods.
-rw-r--r--Lib/test/test_decimal.py28
-rw-r--r--Modules/_decimal/_decimal.c50
2 files changed, 75 insertions, 3 deletions
diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index cde5d78..1aa0bf8 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -5398,6 +5398,34 @@ class CWhitebox(unittest.TestCase):
y = Decimal(10**(9*25)).__sizeof__()
self.assertEqual(y, x+4)
+ def test_internal_use_of_overridden_methods(self):
+ Decimal = C.Decimal
+
+ # Unsound subtyping
+ class X(float):
+ def as_integer_ratio(self):
+ return 1
+ def __abs__(self):
+ return self
+
+ class Y(float):
+ def __abs__(self):
+ return [1]*200
+
+ class I(int):
+ def bit_length(self):
+ return [1]*200
+
+ class Z(float):
+ def as_integer_ratio(self):
+ return (I(1), I(1))
+ def __abs__(self):
+ return self
+
+ for cls in X, Y, Z:
+ self.assertEqual(Decimal.from_float(cls(101.1)),
+ Decimal.from_float(101.1))
+
@requires_docstrings
@unittest.skipUnless(C, "test requires C version")
class SignatureTest(unittest.TestCase):
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index 22053b4..e15941a 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -2208,6 +2208,14 @@ PyDecType_FromLongExact(PyTypeObject *type, const PyObject *pylong,
return dec;
}
+/* External C-API functions */
+static binaryfunc _py_long_multiply;
+static binaryfunc _py_long_floor_divide;
+static ternaryfunc _py_long_power;
+static unaryfunc _py_float_abs;
+static PyCFunction _py_long_bit_length;
+static PyCFunction _py_float_as_integer_ratio;
+
/* Return a PyDecObject or a subtype from a PyFloatObject.
Conversion is exact. */
static PyObject *
@@ -2258,13 +2266,13 @@ PyDecType_FromFloatExact(PyTypeObject *type, PyObject *v,
}
/* absolute value of the float */
- tmp = PyObject_CallMethod(v, "__abs__", NULL);
+ tmp = _py_float_abs(v);
if (tmp == NULL) {
return NULL;
}
/* float as integer ratio: numerator/denominator */
- n_d = PyObject_CallMethod(tmp, "as_integer_ratio", NULL);
+ n_d = _py_float_as_integer_ratio(tmp, NULL);
Py_DECREF(tmp);
if (n_d == NULL) {
return NULL;
@@ -2272,7 +2280,7 @@ PyDecType_FromFloatExact(PyTypeObject *type, PyObject *v,
n = PyTuple_GET_ITEM(n_d, 0);
d = PyTuple_GET_ITEM(n_d, 1);
- tmp = PyObject_CallMethod(d, "bit_length", NULL);
+ tmp = _py_long_bit_length(d, NULL);
if (tmp == NULL) {
Py_DECREF(n_d);
return NULL;
@@ -5511,6 +5519,32 @@ static struct int_constmap int_constants [] = {
#define CHECK_PTR(expr) \
do { if ((expr) == NULL) goto error; } while (0)
+
+static PyCFunction
+cfunc_noargs(PyTypeObject *t, const char *name)
+{
+ struct PyMethodDef *m;
+
+ if (t->tp_methods == NULL) {
+ goto error;
+ }
+
+ for (m = t->tp_methods; m->ml_name != NULL; m++) {
+ if (strcmp(name, m->ml_name) == 0) {
+ if (!(m->ml_flags & METH_NOARGS)) {
+ goto error;
+ }
+ return m->ml_meth;
+ }
+ }
+
+error:
+ PyErr_Format(PyExc_RuntimeError,
+ "internal error: could not find method %s", name);
+ return NULL;
+}
+
+
PyMODINIT_FUNC
PyInit__decimal(void)
{
@@ -5535,6 +5569,16 @@ PyInit__decimal(void)
mpd_setminalloc(_Py_DEC_MINALLOC);
+ /* Init external C-API functions */
+ _py_long_multiply = PyLong_Type.tp_as_number->nb_multiply;
+ _py_long_floor_divide = PyLong_Type.tp_as_number->nb_floor_divide;
+ _py_long_power = PyLong_Type.tp_as_number->nb_power;
+ _py_float_abs = PyFloat_Type.tp_as_number->nb_absolute;
+ ASSIGN_PTR(_py_float_as_integer_ratio, cfunc_noargs(&PyFloat_Type,
+ "as_integer_ratio"));
+ ASSIGN_PTR(_py_long_bit_length, cfunc_noargs(&PyLong_Type, "bit_length"));
+
+
/* Init types */
PyDec_Type.tp_base = &PyBaseObject_Type;
PyDecContext_Type.tp_base = &PyBaseObject_Type;