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Re: [PATCH] xfs: add a few more verifier tests

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>, Eric Sandeen <sandeen@xxxxxxxxxx>
Subject: Re: [PATCH] xfs: add a few more verifier tests
From: Eric Sandeen <sandeen@xxxxxxxxxxx>
Date: Tue, 19 Aug 2014 14:07:39 -0500
Cc: xfs-oss <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20140819181542.GA31177@xxxxxxxxxxxxx>
References: <53F2C103.8030607@xxxxxxxxxx> <20140819181542.GA31177@xxxxxxxxxxxxx>
On 8/19/14, 1:15 PM, Christoph Hellwig wrote:
>> Anyway - bounds checking when we read from disk is a good thing!
> 
> Absolutelt!
> 
> Looks good modulo a few nitpicks below.
> 
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> 
>> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
>> index 4bffffe..a4a9e0e 100644
>> --- a/fs/xfs/libxfs/xfs_alloc.c
>> +++ b/fs/xfs/libxfs/xfs_alloc.c
>> @@ -2209,6 +2209,10 @@ xfs_agf_verify(
>>            be32_to_cpu(agf->agf_flcount) <= XFS_AGFL_SIZE(mp)))
>>              return false;
>>  
>> +    if (!(be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]) <= 
>> XFS_BTREE_MAXLEVELS &&
>> +          be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNT]) <= 
>> XFS_BTREE_MAXLEVELS))
>> +            return false;
> 
> Maybe it's just me, but negated numeric comparisms always confuse the
> hell out of me, why not simply:
> 
>       if (be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]) > XFS_BTREE_MAXLEVELS)
>               return false;
>       if (be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNT]) > XFS_BTREE_MAXLEVELS)
>               return false;
> 
>> --- a/fs/xfs/libxfs/xfs_ialloc.c
>> +++ b/fs/xfs/libxfs/xfs_ialloc.c
>> @@ -2051,6 +2051,8 @@ xfs_agi_verify(
>>      if (!XFS_AGI_GOOD_VERSION(be32_to_cpu(agi->agi_versionnum)))
>>              return false;
>>  
>> +    if (!(be32_to_cpu(agi->agi_level) <= XFS_BTREE_MAXLEVELS))
>> +            return false;
> 
> Same here.

yeah; just following the style of the functions as they exist today...

        if (!(agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&
              XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum)) &&
              be32_to_cpu(agf->agf_freeblks) <= be32_to_cpu(agf->agf_length) &&
...

dunno. Don't care too much either way, but consistency and all that...

Maybe the "AGF_GOOD_VERSION" required the negation, and it all got lumped
together?

Thanks,
-Eric

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