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Message-Id: <20160302170031.C79B634E007@smtpvbsrv1.mitre.org>
Date: Wed,  2 Mar 2016 12:00:31 -0500 (EST)
From: cve-assign@...re.org
To: vdronov@...hat.com
Cc: cve-assign@...re.org, oss-security@...ts.openwall.com
Subject: Re: CVE request -- linux kernel: pipe: limit the per-user amount of pages allocated in pipes

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Hash: SHA256

> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=759c01142a5d0f364a462346168a56de28a80f52

> The result is an OOM condition and oom-killer is not able to help
> much, as the memory for the pipe data is a kernel memory and a memory
> footprint of offensive processes is small.

We feel that this should most likely have a CVE ID. The discussion
outlines a realistic problem "it is possible for a single process to
cause an OOM condition by filling large pipes with data that are never
read. A typical process filling 4000 pipes with 1 MB of data will use
4 GB of memory" and the need for a CVE ID does not depend on the
details of the solution approach. Also, there doesn't seem to be any
general opposition to addressing the problem (e.g., see the
https://lkml.org/lkml/2016/1/19/674 post).

However, the commit indicates that there isn't a mandatory behavior
change ("The limit are controlled by two new sysctls :
pipe-user-pages-soft, and pipe-user-pages-hard. Both may be disabled
by setting them to zero.") -- suggesting a possible interpretation as
a design enhancement, not a vulnerability fix. Also, the discussion
doesn't directly comment on whether the "filling large pipes" scenario
has a security impact that is otherwise unavailable to the attacker,
e.g., it doesn't discuss the difference between the attacker choosing
to fill 4000 pipes and the attacker choosing to use mmap.

Is there anyone who believes 759c01142a5d0f364a462346168a56de28a80f52
must not have a CVE ID?

> The commit says: "Mitigates: CVE-2013-4312 (Linux 2.0+)"

Regardless of any answers to the above question, it is not going to be
useful to use CVE-2013-4312 to refer to
759c01142a5d0f364a462346168a56de28a80f52.

- -- 
CVE assignment team, MITRE CVE Numbering Authority
M/S M300
202 Burlington Road, Bedford, MA 01730 USA
[ PGP key available through http://cve.mitre.org/cve/request_id.html ]
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