From: Dave Chinner <david@fromorbit.com>
To: "zhengbin (A)" <zhengbin13@huawei.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
sandeen@redhat.com, linux-xfs@vger.kernel.org,
renxudong1@huawei.com, "zhangyi (F)" <yi.zhang@huawei.com>
Subject: Re: Questions about XFS abnormal img mount test
Date: Tue, 11 Feb 2020 12:15:38 +1100 [thread overview]
Message-ID: <20200211011538.GC10776@dread.disaster.area> (raw)
In-Reply-To: <ea7db6e3-8a3a-a66d-710c-4854c4e5126c@huawei.com>
On Mon, Feb 10, 2020 at 11:02:08AM +0800, zhengbin (A) wrote:
> ### question
> We recently used fuzz(hydra) to test 4.19 stable XFS and automatically generate tmp.img (XFS v5 format, but some metadata is wrong)
So you create impossible situations in the on-disk format, then
recalculate the CRC to make appear valid to the filesystem?
> Test as follows:
> mount tmp.img tmpdir
> cp file tmpdir
> sync --> stuck
>
> ### cause analysis
> This is because tmp.img (only 1 AG) has some problems. Using xfs_repair detect information as follows:
Please use at least 2 AGs for your fuzzer images. There's no point
in testing single AG filesystems because:
a) they are not supported
b) there is no redundant information in the filesysetm to
be able to detect a vast range of potential corruptions.
> agf_freeblks 0, counted 3224 in ag 0
> agf_longest 536874136, counted 3224 in ag 0
> sb_fdblocks 613, counted 3228
So the AGF verifier is missing these checks:
a) agf_longest < agf_freeblks
b) agf_freeblks < sb_dblocks / sb_agcount
c) agf_freeblks < sb_fdblocks
and probably some other things as well. Can you please add these
checks to xfs_agf_verify() (and any other obvious bounds tests that
are missing) and submit the patch for inclusion?
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2020-02-11 1:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 3:02 Questions about XFS abnormal img mount test zhengbin (A)
2020-02-10 3:59 ` Eric Sandeen
2020-02-11 1:15 ` Dave Chinner [this message]
2020-02-13 8:33 ` zhengbin (A)
2020-02-13 17:11 ` Darrick J. Wong
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