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[2.7] bpo-31478: Prevent unwanted behavior in _random.Random.seed() in case the arg has a bad __abs__() method (GH-3596) (#3845)

This commit is contained in:
Oren Milman 2017-10-03 00:31:42 +03:00 committed by Serhiy Storchaka
parent 20cbc1d29f
commit 13da1a60f1
3 changed files with 26 additions and 2 deletions
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16
Lib/test/test_random.py
View File

@ -307,6 +307,22 @@ class SystemRandom_TestBasicOps(TestBasicOps):
class MersenneTwister_TestBasicOps(TestBasicOps):
gen = random.Random()
@test_support.cpython_only
def test_bug_31478(self):
# _random.Random.seed() should ignore the __abs__() method of a
# long/int subclass argument.
class BadInt(int):
def __abs__(self):
1/0
class BadLong(long):
def __abs__(self):
1/0
self.gen.seed(42)
expected_value = self.gen.random()
for seed_arg in [42L, BadInt(42), BadLong(42)]:
self.gen.seed(seed_arg)
self.assertEqual(self.gen.random(), expected_value)
def test_setstate_first_arg(self):
self.assertRaises(ValueError, self.gen.setstate, (1, None, None))

2
Misc/NEWS.d/next/Core and Builtins/2017-10-01-18-59-40.bpo-31478.owtqoO.rst Normal file
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@ -0,0 +1,2 @@
Prevent unwanted behavior in `_random.Random.seed()` in case the argument
has a bad ``__abs__()`` method. Patch by Oren Milman.

10
Modules/_randommodule.c
View File

@ -230,9 +230,15 @@ random_seed(RandomObject *self, PyObject *args)
}
/* If the arg is an int or long, use its absolute value; else use
* the absolute value of its hash code.
* Calling int.__abs__() or long.__abs__() prevents calling arg.__abs__(),
* which might return an invalid value. See issue #31478.
*/
if (PyInt_Check(arg) || PyLong_Check(arg))
n = PyNumber_Absolute(arg);
if (PyInt_Check(arg)) {
n = PyInt_Type.tp_as_number->nb_absolute(arg);
}
else if (PyLong_Check(arg)) {
n = PyLong_Type.tp_as_number->nb_absolute(arg);
}
else {
long hash = PyObject_Hash(arg);
if (hash == -1)