linux-kernel - Re: [PATCH v2] ocfs2: avoid potential ABBA deadlock by reordering tl

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: <kxo27vjuqawoynwttpg56tzhvxeuobmvgdfglp5g2xcuy4vfnq@t7t4zxq27qon>
Date: Mon, 7 Jul 2025 20:12:49 -0400
From: Ivan Pravdin <ipravdin.official@...il.com>
To: Joseph Qi <joseph.qi@...ux.alibaba.com>, mark@...heh.com, 
	jlbec@...lplan.org, ocfs2-devel@...ts.linux.dev, linux-kernel@...r.kernel.org
Cc: syzbot+6bf948e47f9bac7aacfa@...kaller.appspotmail.com
Subject: Re: [PATCH v2] ocfs2: avoid potential ABBA deadlock by reordering
 tl_inode lock

On Mon, Jul 07, 2025 at 01:58:35PM GMT, Joseph Qi wrote:
> >  	/*
> >  	 * ocfs2_move_extent() didn't reserve any clusters in lock_allocators()
> >  	 * logic, while we still need to lock the global_bitmap.
> > @@ -637,13 +639,11 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
> >  		goto out_unlock_gb_mutex;
> >  	}
> >
> 
> You've missed unlock tl_inode when ocfs2_get_system_file_inode() fails.

I will add it, thanks.

> 
>   
> > -	inode_lock(tl_inode);
> > -
> >  	handle = ocfs2_start_trans(osb, credits);
> >  	if (IS_ERR(handle)) {
> >  		ret = PTR_ERR(handle);
> >  		mlog_errno(ret);
> > -		goto out_unlock_tl_inode;
> > +		goto out_unlock_gb_inode;
> >  	}
> >  
> >  	new_phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, *new_phys_cpos);
> > @@ -704,12 +704,13 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
> >  	ocfs2_commit_trans(osb, handle);
> >  	brelse(gd_bh);
> >  
> > -out_unlock_tl_inode:
> > -	inode_unlock(tl_inode);
> > -
> > +out_unlock_gb_inode:
> >  	ocfs2_inode_unlock(gb_inode, 1);
> > +
> >  out_unlock_gb_mutex:
> 
> inode lock has changed to rw_semaphore, so 'mutex' is no longer proper. 
> 
> >  	inode_unlock(gb_inode);
> > +
> > +	inode_unlock(tl_inode);
> >  	brelse(gb_bh);
> >  	iput(gb_inode);
> >  
> 
> How about the following alternative:
> 
> diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
> index 369c7d27befd..d56c337204f6 100644
> --- a/fs/ocfs2/move_extents.c
> +++ b/fs/ocfs2/move_extents.c
> @@ -611,6 +611,8 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
>  		goto out;
>  	}
>  
> +	inode_lock(tl_inode);
> +
>  	/*
>  	 * need to count 2 extra credits for global_bitmap inode and
>  	 * group descriptor.
> @@ -626,7 +628,7 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
>  	if (!gb_inode) {
>  		mlog(ML_ERROR, "unable to get global_bitmap inode\n");
>  		ret = -EIO;
> -		goto out;
> +		goto out_unlock_tl_inode;
>  	}
>  
>  	inode_lock(gb_inode);
> @@ -634,16 +636,14 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
>  	ret = ocfs2_inode_lock(gb_inode, &gb_bh, 1);
>  	if (ret) {
>  		mlog_errno(ret);
> -		goto out_unlock_gb_mutex;
> +		goto out_unlock_gb_inode;
>  	}
>  
> -	inode_lock(tl_inode);
> -
>  	handle = ocfs2_start_trans(osb, credits);
>  	if (IS_ERR(handle)) {
>  		ret = PTR_ERR(handle);
>  		mlog_errno(ret);
> -		goto out_unlock_tl_inode;
> +		goto out_unlock;
>  	}
>  
>  	new_phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, *new_phys_cpos);
> @@ -703,16 +703,14 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
>  out_commit:
>  	ocfs2_commit_trans(osb, handle);
>  	brelse(gd_bh);
> -
> -out_unlock_tl_inode:
> -	inode_unlock(tl_inode);
> -
> +out_unlock:
>  	ocfs2_inode_unlock(gb_inode, 1);
> -out_unlock_gb_mutex:
> +out_unlock_gb_inode:
>  	inode_unlock(gb_inode);
>  	brelse(gb_bh);
>  	iput(gb_inode);
> -
> +out_unlock_tl_inode:
> +	inode_unlock(tl_inode);
>  out:
>  	if (context->meta_ac) {
>  		ocfs2_free_alloc_context(context->meta_ac);
> 
> 

This is definitely better. I will update the patch, thank you.

	Ivan Pravdin