Re: [vs-plain] Linux kernel stack overflow via ecryptfs and /proc/$pid/environ

[Solar Designer <solar () openwall com>]

On Fri, Jun 10, 2016 at 02:46:23PM -0700, John Johansen wrote:
> This is a forward notification of a local priv escalation flaw from
> security () kernel org to the OSS security list. The CRD was for
> 2016-06-08 14:00:00 UTC. Patches attached to the email.
>
> The flaw in eCryptfs was assigned CVE-2016-1583.

The Project Zero issue is now public:

https://bugs.chromium.org/p/project-zero/issues/detail?id=836

and it includes an exploit, which I've re-attached.  (The rest of the
files, including the crasher, were already posted in here by John.)

> Subject: [PATCH 2/3] ecryptfs: forbid opening files without mmap handler

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2f36db71009304b3f0b95afacd8eba1f9f046b87

> Subject: [PATCH 1/3] proc: prevent stacking filesystems on top

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=e54ad7f1ee263ffa5a2de9c609d58dfa27b21cd9

> Subject: [PATCH 3/3] sched: panic on corrupted stack end

Not committed?

Andy Lutomirski is working on virtually mapped stacks with guard pages
so that kernel stack overflows would be detected:

http://www.openwall.com/lists/kernel-hardening/2016/06/15/1
http://www.openwall.com/lists/kernel-hardening/2016/06/20/14

Linus wants the 1.5us overhead on task creation to be reduced before
this gets merged:

http://www.openwall.com/lists/kernel-hardening/2016/06/21/10

Alexander

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