linux-ext4 - Re: [PATCH 11/11] ext4: remove the access_ok() check in ext4_ioctl_get_es

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Message-Id: <20200501225655.D5C97AE045@d06av26.portsmouth.uk.ibm.com>
Date:   Sat, 2 May 2020 04:26:54 +0530
From:   Ritesh Harjani <riteshh@...ux.ibm.com>
To:     Christoph Hellwig <hch@....de>, linux-ext4@...r.kernel.org,
        viro@...iv.linux.org.uk
Cc:     jack@...e.cz, tytso@....edu, adilger@...ger.ca, amir73il@...il.com,
        linux-fsdevel@...r.kernel.org, linux-unionfs@...r.kernel.org
Subject: Re: [PATCH 11/11] ext4: remove the access_ok() check in
 ext4_ioctl_get_es_cache



On 4/27/20 11:49 PM, Christoph Hellwig wrote:
> access_ok just checks we are fed a proper user pointer.  We also do that
> in copy_to_user itself, so no need to do this early.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>

Looks fine. Feel free to add
Reviewed-by: Ritesh Harjani <riteshh@...ux.ibm.com>


> ---
>   fs/ext4/ioctl.c | 5 -----
>   1 file changed, 5 deletions(-)
> 
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 0746532ba463d..7fded54d2dba9 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -754,11 +754,6 @@ static int ext4_ioctl_get_es_cache(struct file *filp, unsigned long arg)
>   	fieinfo.fi_extents_max = fiemap.fm_extent_count;
>   	fieinfo.fi_extents_start = ufiemap->fm_extents;
>   
> -	if (fiemap.fm_extent_count != 0 &&
> -	    !access_ok(fieinfo.fi_extents_start,
> -		       fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
> -		return -EFAULT;
> -
>   	if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
>   		filemap_write_and_wait(inode->i_mapping);
>   
>