oss-security - Re: Re: CVE request Linux kernel: ns: user namespaces panic

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Message-ID: <87r3pq2has.fsf@x220.int.ebiederm.org>
Date: Fri, 05 Jun 2015 12:31:23 -0500
From: ebiederm@...ssion.com (Eric W. Biederman)
To: P J P <ppandit@...hat.com>
Cc: oss security list <oss-security@...ts.openwall.com>,  cve-assign@...re.org
Subject: Re: Re: CVE request Linux kernel: ns: user namespaces panic

P J P <ppandit@...hat.com> writes:

> +-- On Thu, 4 Jun 2015, cve-assign@...re.org wrote --+
> | >> From: ebiederm@...ssion.com (Eric W. Biederman)
> | >> 
> | >> The core issue is that a unprivileged user could call umount(MNT_DETACH)
> | >> and in the right circumstances gain access to every file on essentially
> | >> any filesystem in the mount namespace.
> | >> 
> | >> e0c9c0afd2fc958ffa34b697972721d81df8a56f mnt: Update detach_mounts to leave mounts connected
> | >> is the real bug fix that fixes a fairly scary issue.
> | >>
> | >> So I believe cd4a40174b71acd021877341684d8bb1dc8ea4ae prevents a
> | >> difficult to trigger crash if you have
> | >> e0c9c0afd2fc958ffa34b697972721d81df8a56f applied.
> | >>
> |
> | Use CVE-2015-4176 for the issue fixed in
> | e0c9c0afd2fc958ffa34b697972721d81df8a56f . This code change is present
> | in 4.0.2.
> | 
> | Use CVE-2015-4177 for the issue fixed in
> | cd4a40174b71acd021877341684d8bb1dc8ea4ae. This code change is not
> | present in 4.0.2.
>
>   Ie IIUC, existence of CVE-2015-4177 depends on CVE-2015-4176 being fixed, 
> which in turn depends on commit
>
>   -> https://git.kernel.org/linus/ce07d891a0891d3c0d0c2d73d577490486b809e1
>
> being present. (...Eric?)

There are no dependencies between
e0c9c0afd2fc958ffa34b697972721d81df8a56f and
cd4a40174b71acd021877341684d8bb1dc8ea4ae

Neither commit (cec9c... or cd4a4017...) missing is a problem unless
ce07d891a0891d3c0d0c2d73d577490486b809e1 is present.

Commits (cec9c... and cd4a4017...) are harmless on their own.

I hope that clarifies things.

Eric

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