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bpo-31478: Fix an assertion failure in random.seed() in case the 'a' arg has a bad __abs__() method #3596

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Merged
merged 5 commits into from
Sep 28, 2017
Merged

bpo-31478: Fix an assertion failure in random.seed() in case the 'a' arg has a bad __abs__() method #3596

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499a26d
init commit
orenmn Sep 15, 2017
448297c
use PyLong_Type.tp_as_number->nb_absolute(arg)
orenmn Sep 23, 2017
0226085
merge master
orenmn Sep 23, 2017
aaca545
add braces
orenmn Sep 23, 2017
852b643
remove cpython_only decorator, and add a comment.
orenmn Sep 23, 2017
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11 changes: 11 additions & 0 deletions Lib/test/test_random.py
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Original file line number Diff line number Diff line change
Expand Up @@ -430,6 +430,17 @@ def test_bug_27706(self):
['0x1.b0580f98a7dbep-1', '0x1.84129978f9c1ap-1',
'0x1.aeaa51052e978p-2', '0x1.092178fb945a6p-2'])

def test_bug_31478(self):
# There shouldn't be an assertion failure in _random.Random.seed() in
# case the argument has a bad __abs__() method.
class BadInt(int):
def __abs__(self):
return None
try:
self.gen.seed(BadInt())
except TypeError:
pass

def test_bug_31482(self):
# Verify that version 1 seeds are unaffected by hash randomization
# when the seeds are expressed as bytes rather than strings.
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2017-09-15-09-13-07.bpo-31478.o06iKD.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix an assertion failure in `_random.Random.seed()` in case the argument has a
bad ``__abs__()`` method. Patch by Oren Milman.
7 changes: 5 additions & 2 deletions Modules/_randommodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -259,8 +259,11 @@ random_seed(RandomObject *self, PyObject *args)
* So: if the arg is a PyLong, use its absolute value.
* Otherwise use its hash value, cast to unsigned.
*/
if (PyLong_Check(arg))
n = PyNumber_Absolute(arg);
if (PyLong_Check(arg)) {
/* Calling int.__abs__() prevents calling arg.__abs__(), which might
return an invalid value. See issue #31478. */
n = PyLong_Type.tp_as_number->nb_absolute(arg);
}
else {
Py_hash_t hash = PyObject_Hash(arg);
if (hash == -1)
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