linux-kernel - Re: [patch] sched: prevent bound kthreads from changing cpus

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]

Date:	Tue, 10 Jun 2008 21:47:50 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Paul Menage <menage@...gle.com>, Paul Jackson <pj@....com>,
	linux-kernel@...r.kernel.org
Subject: Re: [patch] sched: prevent bound kthreads from changing cpus_allowed

On 06/05, David Rientjes wrote:
>
> Kthreads that have called kthread_bind() are bound to specific cpus, so
> other tasks should not be able to change their cpus_allowed from under
> them.  Otherwise, it is possible to move kthreads, such as the migration
> or software watchdog threads, so they are not allowed access to the cpu
> they work on.

Imho, this is very good change, but...

> @@ -180,6 +180,7 @@ void kthread_bind(struct task_struct *k, unsigned int cpu)
>  	set_task_cpu(k, cpu);
>  	k->cpus_allowed = cpumask_of_cpu(cpu);
>  	k->rt.nr_cpus_allowed = 1;
> +	k->flags |= PF_THREAD_BOUND;

What if user-space moves this task right before "|= PF_THREAD_BOUND" ?

Oleg.

--
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/