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Date: Thu, 19 Apr 2012 19:20:45 -0700
From: "Eric W. Biederman" <>
To: Eugene Teo <>,Marcus Meissner <>
CC: OSS Security List <>,,Sukadev Bhattiprolu <>,Serge Hallyn <>,Pavel Emelyanov <>
Subject: Re: CVE request: pid namespace leak in kernel 3.0 and 3.1

Eugene Teo <> wrote:

>On Fri, Apr 20, 2012 at 5:48 AM, Marcus Meissner <>
>> we had a user, Vadim Ponomarev (ccrssaa at,  report a pid
>> namespace leak caused by vsftpd.
>> He provided a simple reproducer:
>> and checking "cat /proc/slabinfo|grep pid_namespace"
>> gives 10000 more active slots after running it on 3.0.13 (+SUSE
>patches) and 3.1.10 (+SUSE patches).
>> Running this on 3.2.0 (+SUSE Patches) did not result in more slots,
>so it was probably
>> fixed between 3.1 and 3.2 (but someone else cross check perhaps).
>> Any idea welcome on which patch fixed this, I tried
>> but it seems not helping.
>I tested this with 3.0.25-rt44.57.el6rt.x86_64 yesterday, and I was
>able to trigger the issue. The process needs to be privileged with
>Eric, besides struct pid_namespace, there is a corresponding struct
>pid_2 leak.


So we know what is holding the pid namespace reference.

Additional thoughts.

Does echo 3 > /proc/sys/vm/drop_caches clear up the issue?

Is there a corresponding task_struct leak?

Are the zombies getting reaped?

I don't have much of a clue or much concern as this seems fixed in later kernels but I am happy to suggest things to look for to help narrow this down.


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