Description
The clone system-call implementation in the Linux kernel before 3.8.3 does not properly handle a combination of the CLONE_NEWUSER and CLONE_FS flags, which allows local users to gain privileges by calling chroot and leveraging the sharing of the / directory between a parent process and a child process.
References
- http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=e66eded8309ebf679d3d3c1f5820d1f2ca332c71
- [oss-security] 20130314 Re: CLONE_NEWUSER|CLONE_FS root exploit mailing-list
- http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.8.3
- http://stealth.openwall.net/xSports/clown-newuser.c
- https://github.com/torvalds/linux/commit/e66eded8309ebf679d3d3c1f5820d1f2ca332c71
- https://bugzilla.redhat.com/show_bug.cgi?id=921448