Re: [PATCH] vfs: check ->get_link return value

From: Dave Chinner <david@fromorbit.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: viro@ZenIV.linux.org.uk, xfs <linux-xfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] vfs: check ->get_link return value
Date: Tue, 2 Oct 2018 09:21:28 +1000	[thread overview]
Message-ID: <20181001232128.GL18567@dastard> (raw)
In-Reply-To: <20181001224500.GE5872@magnolia>

On Mon, Oct 01, 2018 at 03:45:00PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Teach callers of inode->i_op->get_link in the vfs code to check for a
> NULL return value and return an error status instead of blindly
> dereferencing the returned NULL pointer.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/namei.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index 0cab6494978c..0744ab981fa0 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -4737,6 +4737,8 @@ int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
>  		if (IS_ERR(link))
>  			return PTR_ERR(link);
>  	}
> +	if (!link)
> +		return -EUCLEAN;

If we are going to start returning this as a filesystem corruption
error from the VFS, can we please start with adding

#define EFSCORRUPTED	EUCLEAN

into one of the global error definition headers? The code makes much
more sense when it uses EFSCORRUPTED....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com