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From: Qu Wenruo <quwenruo.btrfs@gmx.com>
To: Christoph Hellwig <hch@lst.de>
Cc: dsterba@suse.cz,
	syzbot <syzbot+d2dd123304b4ae59f1bd@syzkaller.appspotmail.com>,
	akpm@linux-foundation.org, clm@fb.com, dsterba@suse.com,
	josef@toxicpanda.com, linux-btrfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, syzkaller-bugs@googlegroups.com,
	willy@infradead.org
Subject: Re: [syzbot] KASAN: use-after-free Read in copy_page_from_iter_atomic (2)
Date: Thu, 16 Jun 2022 05:27:04 +0800	[thread overview]
Message-ID: <00bbda63-dc00-05c0-4244-343352591d98@gmx.com> (raw)
In-Reply-To: <20220615132147.GA18252@lst.de>



On 2022/6/15 21:21, Christoph Hellwig wrote:
> On Tue, Jun 14, 2022 at 04:50:22PM +0800, Qu Wenruo wrote:
>> The same way as data?
>>
>> map-logical to find the location of a mirror, write 4 bytes of zero into
>> the location, then call it a day.
>>
>> Although for metadata, you may want to choose a metadata that would
>> definitely get read.
>> Thus tree root is a good candidate.
>
> And how do I find out the logic address of the tree root?

For tree root, "btrfs ins dump-super <dev> | grep '^root\s'.

For other tree blocks, "btrfs ins dump-tree <dev>" then with other other
keywords to grab.

Thanks,
Qu

  reply	other threads:[~2022-06-15 21:27 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-07 13:11 [syzbot] KASAN: use-after-free Read in copy_page_from_iter_atomic (2) syzbot
2022-06-10  1:24 ` syzbot
2022-06-10  7:10 ` syzbot
2022-06-13 19:39   ` David Sterba
2022-06-14  7:17     ` Christoph Hellwig
2022-06-14  8:50       ` Qu Wenruo
2022-06-15 13:21         ` Christoph Hellwig
2022-06-15 21:27           ` Qu Wenruo [this message]
2022-06-16  6:35             ` Christoph Hellwig
2022-06-16 14:57       ` David Sterba

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