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

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

On 12/11 2013 21:20 PM, Lukáš Czerner wrote:
> On Wed, 11 Dec 2013, Jeff Liu wrote:
> 
>> Date: Wed, 11 Dec 2013 21:10:48 +0800
>> From: Jeff Liu <jeff.liu@oracle.com>
>> To: Lukas Czerner <lczerner@redhat.com>, xfs@oss.sgi.com
>> Subject: Re: [PATCH] xfs: prevent range.len underflow in xfs_ioc_trim()
>>
>> Hi Lukas,
>>
>> Thanks for the fix.  We have corrected this problem with the blow patch
>> which got merged intwo weeks ago. :)
>> [ commit f9fd013561 ]
> 
> Not sure where it got merged, I do not see this upstream in linus
> tree.
Now it resides in xfs-next tree, but I remember Ben have sent out the
pull request "[GIT PULL] XFS bugfixes for 3.13-rc4" to Linus yesterday.

Thanks,
-Jeff
> 
>> xfs: don't perform discard if the given range length is less than block size
>>
>> That is also discovered by generic/288 you contributed.
> 
> Right, I mentioned that in the description.
> 
> -Lukas
> 
>>
>> 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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