[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Thu, 14 Jul 2016 12:26:42 -0400
From: Jessica Frazelle <me@...sfraz.com>
To: oss-security@...ts.openwall.com
Cc: Greg KH <greg@...ah.com>, cve-assign@...re.org
Subject: Re: Re: cve request: local DoS by overflowing kernel
mount table using shared bind mount
it's running systemd in a container... isn't it...
On Thu, Jul 14, 2016 at 12:18 PM, Jessica Frazelle <me@...sfraz.com> wrote:
> what is the use case for mounting /mnt:/mnt in a container?
>
> On Thu, Jul 14, 2016 at 12:15 PM, CAI Qian <caiqian@...hat.com> wrote:
>> Maybe this is a better reproducer using docker. It is exploitable even with
>> user namespace enabled.
>>
>> # docker run -it -v /mnt/:/mnt/:shared --cap-add=SYS_ADMIN rhel7 /bin/bash
>>
>> # cat /proc/self/uid_map
>> 0 995 65536
>>
>> # cat /proc/self/gid_map
>> 0 992 65536
>>
>> (insider container) # for i in `seq 1 20`; mount -o bind /mnt/1 /mnt/2; done
>> CAI Qian
>>
>> ----- Original Message -----
>>> From: "Greg KH" <greg@...ah.com>
>>> To: oss-security@...ts.openwall.com
>>> Cc: caiqian@...hat.com, cve-assign@...re.org
>>> Sent: Wednesday, July 13, 2016 6:45:00 PM
>>> Subject: Re: [oss-security] Re: cve request: local DoS by overflowing kernel mount table using shared bind mount
>>>
>>> On Wed, Jul 13, 2016 at 12:59:40PM -0400, cve-assign@...re.org wrote:
>>> > > It was reported that the mount table expands by a power-of-two
>>> > > with each bind mount command.
>>> >
>>> > > If the system is configured in the way that a non-root user
>>> > > allows bind mount even if with limit number of bind mount
>>> > > allowed, a non-root user could cause a local DoS by quickly
>>> > > overflow the mount table.
>>> >
>>> > > it will cause a deadlock for the whole system,
>>> >
>>> > >> form of unlimited memory consumption that is causing the problem
>>> >
>>> > Use CVE-2016-6213.
>>>
>>> A CVE for an "improperly configured system"? Huh? What distro has such
>>> a configuration set by default? This isn't a kernel bug, so what is
>>> this CVE classified as being "against"? It better not be against the
>>> Linux kernel...
>>>
>>> confused,
>>>
>>> greg k-h
>>>
>
>
>
> --
>
>
> Jessie Frazelle
> 4096R / D4C4 DD60 0D66 F65A 8EFC 511E 18F3 685C 0022 BFF3
> pgp.mit.edu
--
Jessie Frazelle
4096R / D4C4 DD60 0D66 F65A 8EFC 511E 18F3 685C 0022 BFF3
pgp.mit.edu
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
