Re: [PATCH] xfs: prevent range.len underflow in xfs_ioc_trim()

[Jeff Liu <jeff.liu@oracle.com>]

Hi Lukas,

Thanks for the fix.  We have corrected this problem with the blow patch
which got merged intwo weeks ago. :)
[ commit f9fd013561 ]
xfs: don't perform discard if the given range length is less than block size

That is also discovered by generic/288 you contributed.

Thanks,
-Jeff

On 12/11 2013 20:05 PM, Lukas Czerner wrote:
> Currently when range.len is set to 0 it will underflow. Fix it by
> checking for this scenario and return EINVAL in case range.len is
> smaller than block size.
> 
> This was discovered by the xfstests generic/288 and with this patch
> the problem goes away.
> 
> Signed-off-by: Lukas Czerner <lczerner@redhat.com>
> ---
>  fs/xfs/xfs_discard.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
> index 8367d6d..9029082 100644
> --- a/fs/xfs/xfs_discard.c
> +++ b/fs/xfs/xfs_discard.c
> @@ -180,7 +180,8 @@ xfs_ioc_trim(
>  	 * matter as trimming blocks is an advisory interface.
>  	 */
>  	if (range.start >= XFS_FSB_TO_B(mp, mp->m_sb.sb_dblocks) ||
> -	    range.minlen > XFS_FSB_TO_B(mp, XFS_ALLOC_AG_MAX_USABLE(mp)))
> +	    range.minlen > XFS_FSB_TO_B(mp, XFS_ALLOC_AG_MAX_USABLE(mp)) ||
> +	    range.len < XFS_FSB_TO_B(mp, 1))
>  		return -XFS_ERROR(EINVAL);
>  
>  	start = BTOBB(range.start);
> 

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