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From: Cong Wang <xiyou.wangcong@gmail.com>
To: Bryan Jacobs <its@easytoremember.us>
Cc: linux-kernel@vger.kernel.org
Subject: Re: /proc/[pid]/mem write implications
Date: Sun, 29 Jan 2012 11:36:21 +0800	[thread overview]
Message-ID: <4F24BEB5.5070402@gmail.com> (raw)
In-Reply-To: <20120128203250.090abec6@easytoremember.us>

On 01/29/2012 09:32 AM, Bryan Jacobs wrote:
> Dear LKML,
>
> I have a few questions on the recent change to allow writing
> to /proc/[pid]/mem. If I understand correctly, the recent
> privilege-escalation vulnerability was fundamentally caused by
> incorrectly verifying that the memory being written to by a process was
> its own. The goal was to only allow processes to write to their own
> memory space - this was deemed harmless.


Well, the more fundamental vulnerability is the check was done in 
write(2) instead of open(2), which leaves a window for exploits.

>
> But I think that allowing arbitrary processes to write to **their own**
> memory via a file descriptor might in itself be problematic. Please,
> help me understand how this is safe.

You will have a sysctl to control if it is writable.

Thanks.

  reply	other threads:[~2012-01-29  3:36 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-29  1:32 /proc/[pid]/mem write implications Bryan Jacobs
2012-01-29  3:36 ` Cong Wang [this message]
2012-01-29 14:19   ` Alan Cox
2012-01-30  8:10     ` Indan Zupancic
2012-01-29 14:21 ` Alan Cox

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