linux-kernel - Re: [PATCH] signal, procfs: lock_task_sighand() do not need rcu_read

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: <20081003162915.GA624@tv-sign.ru>
Date:	Fri, 3 Oct 2008 20:29:15 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Lai Jiangshan <laijs@...fujitsu.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Alexey Dobriyan <adobriyan@...il.com>
Subject: Re: [PATCH] signal, procfs: lock_task_sighand() do not need rcu_read_lock()

On 10/03, Lai Jiangshan wrote:
>
> lock_task_sighand() make sure task->sighand is being protected,
> so we do not need rcu_read_lock().
> [ exec() will get task->sighand->siglock before change task->sighand! ]
>
> But code using rcu_read_lock() _just_ to protect lock_task_sighand()
> only appear in procfs. (and some code in procfs use lock_task_sighand()
> without such redundant protection.)

Yes, the patch looks correct.

The initial implementaion of lock_task_sighand() did not take RCU lock,
that is why we still have the callers which call rcu_read_lock().
See 1406f2d321bae5ac5ff729dcb773336d9c05ec74.

Thanks!

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/