diff -r ffa851df0825 -r 2fb8b9db1c86 symbian-qemu-0.9.1-12/python-2.6.1/Lib/test/crashers/loosing_mro_ref.py --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/symbian-qemu-0.9.1-12/python-2.6.1/Lib/test/crashers/loosing_mro_ref.py Fri Jul 31 15:01:17 2009 +0100 @@ -0,0 +1,35 @@ +""" +There is a way to put keys of any type in a type's dictionary. +I think this allows various kinds of crashes, but so far I have only +found a convoluted attack of _PyType_Lookup(), which uses the mro of the +type without holding a strong reference to it. Probably works with +super.__getattribute__() too, which uses the same kind of code. +""" + +class MyKey(object): + def __hash__(self): + return hash('mykey') + + def __cmp__(self, other): + # the following line decrefs the previous X.__mro__ + X.__bases__ = (Base2,) + # trash all tuples of length 3, to make sure that the items of + # the previous X.__mro__ are really garbage + z = [] + for i in range(1000): + z.append((i, None, None)) + return -1 + + +class Base(object): + mykey = 'from Base' + +class Base2(object): + mykey = 'from Base2' + +# you can't add a non-string key to X.__dict__, but it can be +# there from the beginning :-) +X = type('X', (Base,), {MyKey(): 5}) + +print X.mykey +# I get a segfault, or a slightly wrong assertion error in a debug build.