linux-kernel - Re: [PATCH] md/linear: rcu_dereference outside read-lock section

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] [day] [month] [year] [list]

Message-ID: <20120814095240.66d30903@notabene.brown>
Date:	Tue, 14 Aug 2012 09:52:40 +1000
From:	NeilBrown <neilb@...e.de>
To:	Denis Efremov <yefremov.denis@...il.com>
Cc:	linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
	ldv-project@...ras.ru
Subject: Re: [PATCH] md/linear: rcu_dereference outside read-lock section

On Tue, 14 Aug 2012 01:08:12 +0400 Denis Efremov <yefremov.denis@...il.com>
wrote:

> According to the comment in linear_stop function
> rcu_dereference in linear_start and linear_stop functions
> occurs under reconfig_mutex. The patch represents this
> agreement in code and prevents lockdep complaint.
> 
> Found by Linux Driver Verification project (linuxtesting.org)
> 
> Signed-off-by: Denis Efremov <yefremov.denis@...il.com>
> ---
>  drivers/md/linear.c |    7 +++++--
>  1 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/md/linear.c b/drivers/md/linear.c
> index fa211d8..093f3e4 100644
> --- a/drivers/md/linear.c
> +++ b/drivers/md/linear.c
> @@ -244,7 +244,8 @@ static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
>  	if (!newconf)
>  		return -ENOMEM;
>  
> -	oldconf = rcu_dereference(mddev->private);
> +	oldconf = rcu_dereference_protected(mddev->private,
> +					    lockdep_is_held(&mddev->reconfig_mutex));
>  	mddev->raid_disks++;
>  	rcu_assign_pointer(mddev->private, newconf);
>  	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
> @@ -256,7 +257,9 @@ static int linear_add(struct mddev *mddev, struct md_rdev *rdev)
>  
>  static int linear_stop (struct mddev *mddev)
>  {
> -	struct linear_conf *conf = mddev->private;
> +	struct linear_conf *conf =
> +		rcu_dereference_protected(mddev->private,
> +					  lockdep_is_held(&mddev->reconfig_mutex));
>  
>  	/*
>  	 * We do not require rcu protection here since


Applied, thanks.

NeilBrown

Download attachment "signature.asc" of type "application/pgp-signature" (829 bytes)