From: Eryu Guan <guaneryu@gmail.com>
To: linux-ext4@vger.kernel.org
Cc: "Theodore Ts'o" <tytso@mit.edu>, "Lukáš Czerner" <lczerner@redhat.com>
Subject: Re: [PATCH v2] ext4: check for overlapping extents in ext4_valid_extent_entries()
Date: Mon, 21 Oct 2013 19:59:54 +0800 [thread overview]
Message-ID: <20131021115954.GA2708@dhcp-13-216.nay.redhat.com> (raw)
In-Reply-To: <1382275647-4616-1-git-send-email-guaneryu@gmail.com>
On Sun, Oct 20, 2013 at 09:27:27PM +0800, Eryu Guan wrote:
> A corrupted ext4 may have out of order leaf extents, i.e.
>
> extent: lblk 0--1023, len 1024, pblk 9217, flags: LEAF UNINIT
> extent: lblk 1000--2047, len 1024, pblk 10241, flags: LEAF UNINIT
> ^^^^ overlap with previous extent
>
> Reading such extent could hit BUG_ON() in ext4_es_cache_extent().
>
> BUG_ON(end < lblk);
>
> The problem is that __read_extent_tree_block() tries to cache holes as
> well but assumes 'lblk' is greater than 'prev' and passes underflowed
> length to ext4_es_cache_extent(). Fix it by checking for overlapping
> extents in ext4_valid_extent_entries().
>
> I hit this when fuzz testing ext4, and am able to reproduce it by
> modifying the on-disk extent by hand.
>
> Ran xfstests on patched ext4 and no regression.
>
> Cc: "Theodore Ts'o" <tytso@mit.edu>
> Cc: Lukáš Czerner <lczerner@redhat.com>
> Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Self NAK, I found problems in tests, will think about it more.
Thanks,
Eryu
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next prev parent reply other threads:[~2013-10-21 11:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-17 9:27 [PATCH] ext4: don't cache out of order extents Eryu Guan
2013-10-17 13:44 ` Lukáš Czerner
2013-10-17 14:40 ` Theodore Ts'o
2013-10-17 15:22 ` Lukáš Czerner
2013-10-17 15:58 ` Theodore Ts'o
2013-10-17 15:06 ` Eryu Guan
2013-10-20 13:27 ` [PATCH v2] ext4: check for overlapping extents in ext4_valid_extent_entries() Eryu Guan
2013-10-21 11:59 ` Eryu Guan [this message]
2013-10-21 12:47 ` Eryu Guan
2013-10-21 16:06 ` Lukáš Czerner
2013-10-22 18:40 ` Eryu Guan
2013-12-04 2:36 ` [PATCH v3] " Theodore Ts'o
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