[LTP] [PATCH v3 1/3] security/dirtyc0w: Fix bug caused by default umask

Cyril Hrubis
2020-03-30T09:20:46Z

Hi!
> > The case is only successful when system default umask is 0022.
> > When default umask is 0077 or other values, should clear current umask by umask(0) in setup().
>
> What exactly fails in the dirtyc0w because of non-standard umask?
>
> I can easily understand why fstat and statx fail, since we check the
> file permissions there. Ideally the failure should have been part of the
> patch description.

Looking at the code I guess that the child fails to open the file
created in parent before the setgid/setuid, something like this should
really have been part of the patch description.

--
Cyril Hrubis
chrubis@suse.cz