linux-kernel - Re: [RFC][PATCH] fix move/migrate

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: <4F480326.8070706@linux.vnet.ibm.com>
Date:	Fri, 24 Feb 2012 13:37:42 -0800
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	Christoph Lameter <cl@...ux.com>
CC:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC][PATCH] fix move/migrate_pages() race on task struct

On 02/24/2012 09:32 AM, Christoph Lameter wrote:
> @@ -1318,10 +1318,10 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pi
>  	rcu_read_lock();
>  	task = pid ? find_task_by_vpid(pid) : current;
>  	if (!task) {
> -		rcu_read_unlock();
>  		err = -ESRCH;
>  		goto out;
>  	}
...
> +	put_task_struct(task);
> +	task = NULL;
>  	err = do_migrate_pages(mm, old, new,
>  		capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
>  out:
> +	if (task)
> +		put_task_struct(task);
> +
>  	if (mm)
>  		mmput(mm);
>  	NODEMASK_SCRATCH_FREE(scratch);

Man, patch did not like this for some reason.  I kept throwing most of
the mempolicy.c hunks away.  I've never seen anything like it.

Anyway...  This looks fine except I think that rcu_read_unlock() need to
stay.  There's currently no release of it after out:.

--
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/