linux-kernel - Re: [PATCH 1/1 linux-next] udf: return inappropriate ioctl instead of argument error

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Date:   Fri, 20 Jan 2017 11:19:44 +0100
From:   Jan Kara <jack@...e.cz>
To:     Fabian Frederick <fabf@...net.be>
Cc:     Jan Kara <jack@...e.cz>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/1 linux-next] udf: return inappropriate ioctl instead
 of argument error

On Thu 19-01-17 21:41:37, Fabian Frederick wrote:
> Currently, lsattr for instance in udf directory gives
> "udf: Invalid argument While reading flags on ..."
> 
> This patch removes argument testing and returns -ENOIOCTLCMD
> when command is unknown to have more accurate message like this:
> "Inappropriate ioctl for device While reading flags on ..."
> If arg is NULL, we return specific operation error anyway.

OK, ENOIOCTLCMD is better than EINVAL but for the case of NULL argument for
correct ioctl command you should keep the check so that we don't fault and
kill the caller instead of returning EINVAL as we used to...

								Honza
> 
> Signed-off-by: Fabian Frederick <fabf@...net.be>
> ---
>  fs/udf/file.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/udf/file.c b/fs/udf/file.c
> index dbcb3a4a..964620b 100644
> --- a/fs/udf/file.c
> +++ b/fs/udf/file.c
> @@ -184,12 +184,6 @@ long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  		goto out;
>  	}
>  
> -	if (!arg) {
> -		udf_debug("invalid argument to udf_ioctl\n");
> -		result = -EINVAL;
> -		goto out;
> -	}
> -
>  	switch (cmd) {
>  	case UDF_GETVOLIDENT:
>  		if (copy_to_user((char __user *)arg,
> @@ -220,6 +214,8 @@ long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  				      UDF_I(inode)->i_ext.i_data,
>  				      UDF_I(inode)->i_lenEAttr) ? -EFAULT : 0;
>  		goto out;
> +	default:
> +		return -ENOIOCTLCMD;
>  	}
>  
>  out:
> -- 
> 2.9.3
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR