From mboxrd@z Thu Jan  1 00:00:00 1970
From: Steve Grubb <sgrubb@redhat.com>
Subject: Re: [oss-security] CVE request: Another Linux syscall auditing bug
Date: Thu, 19 Jun 2014 23:37:39 -0400
Message-ID: <5505250.3yQZm9nuEg@x2>
References: <CALCETrVuwhQ1CST8dbaUYTDFtOn36Nts-SzPV+Uwz=qiXoiTtg@mail.gmail.com>
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Cc: Linux Audit <linux-audit@redhat.com>, Andy Lutomirski <luto@amacapital.net>
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Hi,

Reminder again...please report bugs to linux-audit mail list.

On Thursday, June 19, 2014 06:26:38 PM Andy Lutomirski wrote:
> On a 32-bit x86 kernel with syscall auditing enabled, syscall(1000)
> will cause an OOPS.  This problem goes at least as far back as Linux
> 3.11 and appears to be present in Linux 3.15 as well.  I suspect that
> this bug is very old.
> =

> In order to see this bug, you'll need syscall auditing on (auditctl -e
> 1 will do that) and you'll need 'sep' in flags in /proc/cpuinfo.  That
> means that qemu -cpu qemu64 will not be exposed to this bug, but qemu
> -cpu host will on any recent CPU.
> =

> Mitigations include:
>  - Running under ptrace or strace.
>  - Using any seccomp filter at all (phew!)
>  - Turning off SEP (which is a big slowdown on all syscalls)
>  - auditctl -a task,never
> =

> I'd be rather surprised if this can be used for anything other than
> DoS, although the same underlying bug could potentially have more
> serious consequences.
> =

> This bug was found (inadvertently, I presume) by Toralf F=F6rster.  The
> patch here:
> =

> http://lkml.kernel.org/g/CALCETrW7U4AHG-a9oPbOt31z3wgzhjSu8b+yGpdM4+vNinK=
gsA
> @mail.gmail.com
> =

> is reported to fix the bug, but it should not be considered to be
> well-tested.
> =

> --Andy