[issue9869] long_subtype_new segfault in pure-Python code
Mark Dickinson dicki...@gmail.com added the comment: Right. In practice, returning a long instead of an int can produce bugs, mainly because some C functions will only accept ints and refuse longs. I'd say 'in theory' rather than 'in practice' here. In this particular case, I don't see much danger: any C code explicitly calling PyNumber_Long (rather than PyNumber_Int) surely has to be prepared to deal with a long, since that's what's going to be returned in the vast majority of cases. Similarly for Python code calling 'long' rather than 'int'. I'd also note that the docs state clearly that PyNumber_Long returns a long (while PyNumber_Int, in contrast, is permitted to return either an int or a long); similarly for the builtin 'long' function. And finally, looking at the history of the test_class test (see issue 1671298), it doesn't look as if anyone was thinking too hard about return types at that point---it looks like the test was just fit to the existing semi-broken behaviour. So I'm still proposing to apply this patch, in spite of Antoine's -1. ;-) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9869] long_subtype_new segfault in pure-Python code
Mark Dickinson dicki...@gmail.com added the comment: Committed in r85016. I'll take responsibility for any broken 3rd party code... -- resolution: - fixed status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9869] long_subtype_new segfault in pure-Python code
Mark Dickinson dicki...@gmail.com added the comment: Problem confirmed here; thanks for the report. I think it's also a bug that after: class A(object): def __long__(self): return 42 long(A()) returns an object of type 'int' rather than an object of type 'long'. It's inconsistent with what happens with __trunc__, too: class A(object): ... def __trunc__(self): return 42 ... [37198 refs] long(A()) 42L [37201 refs] What's a little bit odd is that there's a test for the __long__-returning-int behaviour in test_class that asserts the return type should be int. Here's a patch that fixes the return type of long (and PyNumber_Long) to be long in these cases. -- keywords: +patch Added file: http://bugs.python.org/file18918/issue9869.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9869] long_subtype_new segfault in pure-Python code
Mark Dickinson dicki...@gmail.com added the comment: Removing 2.6 from the versions, since this isn't a security problem (as far as I know). -- versions: -Python 2.6 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9869] long_subtype_new segfault in pure-Python code
Antoine Pitrou pit...@free.fr added the comment: What's a little bit odd is that there's a test for the __long__- returning-int behaviour in test_class that asserts the return type should be int. If there is a test then the behaviour is probably deliberate, and changing it would break compatibility. -- nosy: +pitrou ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9869] long_subtype_new segfault in pure-Python code
Eric Smith e...@trueblade.com added the comment: There are plenty of tests that check implementation specific internal behaviors. I don't think the presence of test alone would mean that it can't be changed. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9869] long_subtype_new segfault in pure-Python code
Antoine Pitrou pit...@free.fr added the comment: There are plenty of tests that check implementation specific internal behaviors. I don't think the presence of test alone would mean that it can't be changed. Right. In practice, returning a long instead of an int can produce bugs, mainly because some C functions will only accept ints and refuse longs. (which is the C functions' fault, but unless you want to find and fix all of them (including perhaps in 3rd-party libraries), I think it's better not to change the current behaviour) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9869] long_subtype_new segfault in pure-Python code
New submission from Carl Witty carl.wi...@gmail.com: PyNumber_Long() (and hence long_new()) are willing to return ints, rather than longs. However, when long_subtype_new() calls long_new(), it casts the result to PyLongObject* without a check. (Well, there is an assertion, so if assertions are enabled you'd get an assertion failure instead of a potential segmentation fault.) The attached program segfaults for me; returning smaller numbers than 100 sometimes gives bad answers instead of crashing. -- components: Interpreter Core files: python_long_bug.py messages: 116514 nosy: cwitty priority: normal severity: normal status: open title: long_subtype_new segfault in pure-Python code type: crash versions: Python 2.5, Python 2.6, Python 2.7 Added file: http://bugs.python.org/file18899/python_long_bug.py ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9869] long_subtype_new segfault in pure-Python code
Changes by Mark Dickinson dicki...@gmail.com: -- assignee: - mark.dickinson nosy: +mark.dickinson priority: normal - high ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9869] long_subtype_new segfault in pure-Python code
Changes by Eric Smith e...@trueblade.com: -- nosy: +eric.smith versions: -Python 2.5 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9869 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
