https://github.com/python/cpython/commit/796cc6e3ad3617c1ea9e528663aac1a2062... commit: 796cc6e3ad3617c1ea9e528663aac1a206230a28 branch: master author: Thomas Perl <m@thp.io> committer: Inada Naoki <songofacandy@gmail.com> date: 2019-03-28T15:03:25+09:00 summary: bpo-36452: dictiter: track maximum iteration count (GH-12596) files: A Misc/NEWS.d/next/Core and Builtins/2019-03-27-23-53-00.bpo-36452.xhK2lT.rst M Lib/test/test_dict.py M Objects/dictobject.c diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py index 03afd5b2a6c7..eecdc8beec69 100644 --- a/Lib/test/test_dict.py +++ b/Lib/test/test_dict.py @@ -470,6 +470,15 @@ def test_mutating_iteration(self): for i in d: d[i+1] = 1 + def test_mutating_iteration_delete(self): + # change dict content during iteration + d = {} + d[0] = 0 + with self.assertRaises(RuntimeError): + for i in d: + del d[0] + d[1] = 1 + def test_mutating_lookup(self): # changing dict during a lookup (issue #14417) class NastyKey: diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-03-27-23-53-00.bpo-36452.xhK2lT.rst b/Misc/NEWS.d/next/Core and Builtins/2019-03-27-23-53-00.bpo-36452.xhK2lT.rst new file mode 100644 index 000000000000..37c0c503edec --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2019-03-27-23-53-00.bpo-36452.xhK2lT.rst @@ -0,0 +1 @@ +Changing `dict` keys during iteration will now be detected in certain corner cases where the number of keys isn't changed (but they keys themselves are), and a `RuntimeError` will be raised. \ No newline at end of file diff --git a/Objects/dictobject.c b/Objects/dictobject.c index e2603e190b62..7ea979cd1761 100644 --- a/Objects/dictobject.c +++ b/Objects/dictobject.c @@ -3543,6 +3543,12 @@ dictiter_iternextkey(dictiterobject *di) goto fail; key = entry_ptr->me_key; } + // We found an element (key), but did not expect it + if (di->len == 0) { + PyErr_SetString(PyExc_RuntimeError, + "dictionary keys changed during iteration"); + goto fail; + } di->di_pos = i+1; di->len--; Py_INCREF(key);