linux-kernel - Re: [PATCH] hfsplus: stop workqueue when fill

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Date:   Tue, 15 May 2018 13:26:21 -0300
From:   Ernesto A. Fernández 
        <ernesto.mnd.fernandez@...il.com>
To:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:     syzbot <syzbot+4f2e5f086147d543ab03@...kaller.appspotmail.com>,
        syzkaller-bugs@...glegroups.com, Al Viro <viro@...iv.linux.org.uk>,
        akpm@...ux-foundation.org, dhowells@...hat.com,
        ernesto.mnd.fernandez@...il.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, slava@...eyko.com
Subject: Re: [PATCH] hfsplus: stop workqueue when fill_super() failed

On Tue, May 15, 2018 at 07:11:06PM +0900, Tetsuo Handa wrote:
> From ffd64dcf946502e7bb1d23c021ee9a4fc92f9312 Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Date: Tue, 15 May 2018 12:23:03 +0900
> Subject: [PATCH] hfsplus: stop workqueue when fill_super() failed
> 
> syzbot is reporting ODEBUG messages at hfsplus_fill_super() [1].
> This is because hfsplus_fill_super() forgot to call
> cancel_delayed_work_sync().
> 
> As far as I can see, it is hfsplus_mark_mdb_dirty() from
> hfsplus_new_inode() in hfsplus_fill_super() that calls
> queue_delayed_work(). Therefore, I assume that hfsplus_new_inode() does not
> fail if queue_delayed_work() was called, and the out_put_hidden_dir label
> is the appropriate location to call cancel_delayed_work_sync().
> 
> [1] https://syzkaller.appspot.com/bug?id=a66f45e96fdbeb76b796bf46eb25ea878c42a6c9
> 
> Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Reported-by: syzbot <syzbot+4f2e5f086147d543ab03@...kaller.appspotmail.com>
> Cc: Al Viro <viro@...iv.linux.org.uk>
> ---
>  fs/hfsplus/super.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
> index 9e690ae..80abba5 100644
> --- a/fs/hfsplus/super.c
> +++ b/fs/hfsplus/super.c
> @@ -590,6 +590,7 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent)
>  	return 0;
>  
>  out_put_hidden_dir:
> +	cancel_delayed_work_sync(&sbi->sync_work);
>  	iput(sbi->hidden_dir);
>  out_put_root:
>  	dput(sb->s_root);
> -- 
> 1.8.3.1
> 
> 

I sent this same patch a couple of weeks ago:

https://www.spinics.net/lists/linux-fsdevel/msg125240.html

I should probably have sent it in reply to syzbot to prevent this kind of
duplication of work. Sorry about that.