linux-ext4 - Re: [PATCH] fs/ext{3,4}: fix potential race when setversion ioctl updates inode

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Date:	Wed, 4 Jan 2012 18:46:09 +0100
From:	Jan Kara <jack@...e.cz>
To:	Djalal Harouni <tixxdz@...ndz.org>
Cc:	Jan Kara <jack@...e.cz>, Andrew Morton <akpm@...ux-foundation.org>,
	Andreas Dilger <adilger.kernel@...ger.ca>,
	Theodore Ts'o <tytso@....edu>,
	Yongqiang Yang <xiaoqiangnk@...il.com>,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] fs/ext{3,4}: fix potential race when setversion ioctl
 updates inode

On Tue 03-01-12 02:31:52, Djalal Harouni wrote:
> 
> The EXT{3,4}_IOC_SETVERSION ioctl() updates the inode without i_mutex,
> this can lead to a race with the other operations that update the same
> inode.
> 
> Patch tested.
  OK, so I've taken the patch into my tree, just updated the changelog
which result of our discussion in this thread. I also took the ext4 part
since there is no risk of conflict and the patch looks obvious.

								Honza

> Signed-off-by: Djalal Harouni <tixxdz@...ndz.org>
> ---
>  fs/ext3/ioctl.c |    6 +++++-
>  fs/ext4/ioctl.c |    6 +++++-
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext3/ioctl.c b/fs/ext3/ioctl.c
> index ba1b54e..e7b2ed9 100644
> --- a/fs/ext3/ioctl.c
> +++ b/fs/ext3/ioctl.c
> @@ -134,10 +134,11 @@ flags_out:
>  			goto setversion_out;
>  		}
>  
> +		mutex_lock(&inode->i_mutex);
>  		handle = ext3_journal_start(inode, 1);
>  		if (IS_ERR(handle)) {
>  			err = PTR_ERR(handle);
> -			goto setversion_out;
> +			goto unlock_out;
>  		}
>  		err = ext3_reserve_inode_write(handle, inode, &iloc);
>  		if (err == 0) {
> @@ -146,6 +147,9 @@ flags_out:
>  			err = ext3_mark_iloc_dirty(handle, inode, &iloc);
>  		}
>  		ext3_journal_stop(handle);
> +
> +unlock_out:
> +		mutex_unlock(&inode->i_mutex);
>  setversion_out:
>  		mnt_drop_write(filp->f_path.mnt);
>  		return err;
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index a567968..46a8de6 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -158,10 +158,11 @@ flags_out:
>  			goto setversion_out;
>  		}
>  
> +		mutex_lock(&inode->i_mutex);
>  		handle = ext4_journal_start(inode, 1);
>  		if (IS_ERR(handle)) {
>  			err = PTR_ERR(handle);
> -			goto setversion_out;
> +			goto unlock_out;
>  		}
>  		err = ext4_reserve_inode_write(handle, inode, &iloc);
>  		if (err == 0) {
> @@ -170,6 +171,9 @@ flags_out:
>  			err = ext4_mark_iloc_dirty(handle, inode, &iloc);
>  		}
>  		ext4_journal_stop(handle);
> +
> +unlock_out:
> +		mutex_unlock(&inode->i_mutex);
>  setversion_out:
>  		mnt_drop_write(filp->f_path.mnt);
>  		return err;
> -- 
> 1.7.1
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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