linux-kernel - Re: [PATCH] ocfs2: cancel dqi_sync

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Message-ID: <0d6730e8-9a58-45ba-9e57-c22039f03253@suse.com>
Date: Wed, 4 Sep 2024 10:56:18 +0800
From: Heming Zhao <heming.zhao@...e.com>
To: Joseph Qi <joseph.qi@...ux.alibaba.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: ocfs2-devel@...ts.linux.dev, linux-kernel@...r.kernel.org,
 syzbot+f7af59df5d6b25f0febd@...kaller.appspotmail.com
Subject: Re: [PATCH] ocfs2: cancel dqi_sync_work before freeing oinfo

On 9/4/24 10:09, Joseph Qi wrote:
> ocfs2_global_read_info() will schedule dqi_sync_work. So any error
> occurs after it, we have to cancel this delayed work first before
> freeing oinfo, otherwise it will trigger the following warning with
> CONFIG_DEBUG_OBJECTS_* enabled:
> 
> ODEBUG: free active (active state 0) object: 00000000d8b0ce28 object type: timer_list hint: qsync_work_fn+0x0/0x16c
> 
> Link: https://syzkaller.appspot.com/bug?extid=f7af59df5d6b25f0febd
> Reported-by: syzbot+f7af59df5d6b25f0febd@...kaller.appspotmail.com
> Tested-by: syzbot+f7af59df5d6b25f0febd@...kaller.appspotmail.com
> Fixes: 171bf93ce11f ("ocfs2: Periodic quota syncing")
> Cc: stable@...r.kernel.org
> Signed-off-by: Joseph Qi <joseph.qi@...ux.alibaba.com>
> ---
>   fs/ocfs2/quota_local.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
> index 8ce462c64c51..ebe0dbc8db4a 100644
> --- a/fs/ocfs2/quota_local.c
> +++ b/fs/ocfs2/quota_local.c
> @@ -782,6 +782,7 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
>   		if (locked)
>   			ocfs2_inode_unlock(lqinode, 1);
>   		ocfs2_release_local_quota_bitmaps(&oinfo->dqi_chunk);
> +		cancel_delayed_work_sync(&oinfo->dqi_sync_work);
>   		kfree(oinfo);
>   	}
>   	brelse(bh);

In my view, there is one problem:
If ocfs2_global_read_info() returns error before ->dqi_sync_work is
initialized, above code will trigger wild pointer error.

-Heming