linux-ext4 - Re: [PATCH 4/5] overlayfs: Check for range bounds before calling i

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Date:   Thu, 23 Apr 2020 13:19:51 +0200
From:   Jan Kara <jack@...e.cz>
To:     Ritesh Harjani <riteshh@...ux.ibm.com>
Cc:     linux-ext4@...r.kernel.org, jack@...e.cz, tytso@....edu,
        adilger@...ger.ca, darrick.wong@...cle.com, hch@...radead.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Murphy Zhou <jencce.kernel@...il.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        Amir Goldstein <amir73il@...il.com>,
        linux-fsdevel@...r.kernel.org, linux-unionfs@...r.kernel.org
Subject: Re: [PATCH 4/5] overlayfs: Check for range bounds before calling
 i_op->fiemap()

On Thu 23-04-20 16:17:56, Ritesh Harjani wrote:
> Underlying fs may not be able to handle the length in fiemap
> beyond sb->s_maxbytes. So similar to how VFS ioctl does it,
> add fiemap_check_ranges() check in ovl_fiemap() as well
> before calling underlying fs i_op->fiemap() call.
> 
> Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>
> ---
>  fs/overlayfs/inode.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

Yeah, makes sense. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> 
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index 79e8994e3bc1..9bcd2e96faad 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -455,16 +455,21 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
>  	int err;
>  	struct inode *realinode = ovl_inode_real(inode);
>  	const struct cred *old_cred;
> +	u64 length;
>  
>  	if (!realinode->i_op->fiemap)
>  		return -EOPNOTSUPP;
>  
> +	err = fiemap_check_ranges(realinode->i_sb, start, len, &length);
> +	if (err)
> +		return err;
> +
>  	old_cred = ovl_override_creds(inode->i_sb);
>  
>  	if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC)
>  		filemap_write_and_wait(realinode->i_mapping);
>  
> -	err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
> +	err = realinode->i_op->fiemap(realinode, fieinfo, start, length);
>  	revert_creds(old_cred);
>  
>  	return err;
> -- 
> 2.21.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR