linux-kernel - Re: [ckrm-tech] [RFC][PATCH][2/4] Add RSS accounting and control

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <45D9AFBE.5020107@in.ibm.com>
Date:	Mon, 19 Feb 2007 19:40:06 +0530
From:	Balbir Singh <balbir@...ibm.com>
To:	Paul Menage <menage@...gle.com>
CC:	vatsa@...ibm.com, ckrm-tech@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, xemul@...ru, linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	svaidy@...ux.vnet.ibm.com, devel@...nvz.org
Subject: Re: [ckrm-tech] [RFC][PATCH][2/4] Add RSS accounting and control

Paul Menage wrote:
> On 2/19/07, Balbir Singh <balbir@...ibm.com> wrote:
>>> More worrisome is the potential for use-after-free.  What prevents the
>>> pointer at mm->container from referring to freed memory after we're dropped
>>> the lock?
>>>
>> The container cannot be freed unless all tasks holding references to it are
>> gone,
> 
> ... or have been moved to other containers. If you're not holding
> task->alloc_lock or one of the container mutexes, there's nothing to
> stop the task being moved to another container, and the container
> being deleted.
> 
> If you're in an RCU section then you can guarantee that the container
> (that you originally read from the task) and its subsystems at least
> won't be deleted while you're accessing them, but for accounting like
> this I suspect that's not enough, since you need to be adding to the
> accounting stats on the correct container. I think you'll need to hold
> mm->container_lock for the duration of memctl_update_rss()
> 
> Paul
> 

Yes, that sounds like the correct thing to do.

-- 
	Warm Regards,
	Balbir Singh
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/