[PATCH] xfs: avoid underflow in xfs_ioc_trim()

[Carlos Maiolino]

On Tue, Oct 09, 2012 at 02:15:45PM +0200, Lukas Czerner wrote:
> Currently if len argument in xfs_ioc_trim() is smaller than one BB
> (basic block) the 'end' variable underflow. Avoid that by bailing out if
> len is smaller than BB.
> 
> Signed-off-by: Lukas Czerner <lczerner at redhat.com>
> ---
>  fs/xfs/xfs_discard.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
> index 69cf4fc..54dc58a 100644
> --- a/fs/xfs/xfs_discard.c
> +++ b/fs/xfs/xfs_discard.c
> @@ -183,8 +183,12 @@ xfs_ioc_trim(
>  	    range.minlen > XFS_FSB_TO_B(mp, XFS_ALLOC_AG_MAX_USABLE(mp)))
>  		return -XFS_ERROR(EINVAL);
>  
> +	end = BTOBBT(range.len);
> +	if (0 == end)
> +		goto out;
> +
>  	start = BTOBB(range.start);
> -	end = start + BTOBBT(range.len) - 1;
> +	end += start - 1;
>  	minlen = BTOBB(max_t(u64, granularity, range.minlen));
>  
>  	if (end > XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks) - 1)
> @@ -203,6 +207,7 @@ xfs_ioc_trim(
>  	if (last_error)
>  		return last_error;
>  
> +out:
>  	range.len = XFS_FSB_TO_B(mp, blocks_trimmed);
>  	if (copy_to_user(urange, &range, sizeof(range)))
>  		return -XFS_ERROR(EFAULT);
> -- 
> 1.7.7.6
> 
> _______________________________________________
> xfs mailing list
> xfs at oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

Looks good,

Reviewed-by: Carlos Maiolino <cmaiolino at redhat.com>
-- 
--Carlos