From: Christoph Hellwig <hch@lst.de>
To: Yu Kuai <yukuai1@huaweicloud.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Alasdair Kergon <agk@redhat.com>,
Mike Snitzer <snitzer@kernel.org>,
dm-devel@redhat.com, linux-block@vger.kernel.org,
"yukuai (C)" <yukuai3@huawei.com>
Subject: Re: [PATCH 7/7] block: store the holder kobject in bd_holder_disk
Date: Tue, 1 Nov 2022 11:49:27 +0100 [thread overview]
Message-ID: <20221101104927.GA13823@lst.de> (raw)
In-Reply-To: <fd409996-e5e1-d7af-b31d-87db943eaa25@huaweicloud.com>
On Mon, Oct 31, 2022 at 09:52:04AM +0800, Yu Kuai wrote:
>> INIT_LIST_HEAD(&holder->list);
>> - holder->bdev = bdev;
>> holder->refcnt = 1;
>> + holder->holder_dir = kobject_get(bdev->bd_holder_dir);
>
> I wonder is this safe here, if kobject reference is 0 here and
> bd_holder_dir is about to be freed. Here in kobject_get, kref_get() will
> warn about uaf, and kobject_get will return a address that is about to
> be freed.
But how could the reference be 0 here? The driver that calls
bd_link_disk_holder must have the block device open and thus hold a
reference to it.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Yu Kuai <yukuai1@huaweicloud.com>
Cc: Jens Axboe <axboe@kernel.dk>, Mike Snitzer <snitzer@kernel.org>,
linux-block@vger.kernel.org, dm-devel@redhat.com,
"yukuai \(C\)" <yukuai3@huawei.com>,
Christoph Hellwig <hch@lst.de>, Alasdair Kergon <agk@redhat.com>
Subject: Re: [dm-devel] [PATCH 7/7] block: store the holder kobject in bd_holder_disk
Date: Tue, 1 Nov 2022 11:49:27 +0100 [thread overview]
Message-ID: <20221101104927.GA13823@lst.de> (raw)
In-Reply-To: <fd409996-e5e1-d7af-b31d-87db943eaa25@huaweicloud.com>
On Mon, Oct 31, 2022 at 09:52:04AM +0800, Yu Kuai wrote:
>> INIT_LIST_HEAD(&holder->list);
>> - holder->bdev = bdev;
>> holder->refcnt = 1;
>> + holder->holder_dir = kobject_get(bdev->bd_holder_dir);
>
> I wonder is this safe here, if kobject reference is 0 here and
> bd_holder_dir is about to be freed. Here in kobject_get, kref_get() will
> warn about uaf, and kobject_get will return a address that is about to
> be freed.
But how could the reference be 0 here? The driver that calls
bd_link_disk_holder must have the block device open and thus hold a
reference to it.
--
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dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel
next prev parent reply other threads:[~2022-11-01 10:49 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-30 15:31 fix delayed holder tracking v2 Christoph Hellwig
2022-10-30 15:31 ` [dm-devel] " Christoph Hellwig
2022-10-30 15:31 ` [PATCH 1/7] block: clear ->slave_dir when dropping the main slave_dir reference Christoph Hellwig
2022-10-30 15:31 ` [dm-devel] " Christoph Hellwig
2022-10-30 15:31 ` [PATCH 2/7] dm: remove free_table_devices Christoph Hellwig
2022-10-30 15:31 ` [dm-devel] " Christoph Hellwig
2022-10-30 15:31 ` [PATCH 3/7] dm: cleanup open_table_device Christoph Hellwig
2022-10-30 15:31 ` [dm-devel] " Christoph Hellwig
2022-10-30 15:31 ` [PATCH 4/7] dm: cleanup close_table_device Christoph Hellwig
2022-10-30 15:31 ` [dm-devel] " Christoph Hellwig
2022-10-30 15:31 ` [PATCH 5/7] dm: track per-add_disk holder relations in DM Christoph Hellwig
2022-10-30 15:31 ` [dm-devel] " Christoph Hellwig
2022-11-09 2:08 ` Yu Kuai
2022-11-09 2:08 ` [dm-devel] " Yu Kuai
2022-11-09 8:26 ` Christoph Hellwig
2022-11-09 8:26 ` [dm-devel] " Christoph Hellwig
2022-11-10 18:09 ` Mike Snitzer
2022-11-10 18:09 ` [dm-devel] " Mike Snitzer
2022-11-10 19:48 ` Mike Snitzer
2022-11-10 19:48 ` Mike Snitzer
2022-11-12 6:23 ` Yu Kuai
2022-11-12 6:23 ` [dm-devel] " Yu Kuai
2022-10-30 15:31 ` [PATCH 6/7] block: remove delayed holder registration Christoph Hellwig
2022-10-30 15:31 ` [dm-devel] " Christoph Hellwig
2022-10-30 15:31 ` [PATCH 7/7] block: store the holder kobject in bd_holder_disk Christoph Hellwig
2022-10-30 15:31 ` [dm-devel] " Christoph Hellwig
2022-10-31 1:52 ` Yu Kuai
2022-10-31 1:52 ` [dm-devel] " Yu Kuai
2022-11-01 10:49 ` Christoph Hellwig [this message]
2022-11-01 10:49 ` Christoph Hellwig
2022-11-01 11:12 ` Yu Kuai
2022-11-01 11:12 ` [dm-devel] " Yu Kuai
2022-11-01 11:21 ` Christoph Hellwig
2022-11-01 11:21 ` [dm-devel] " Christoph Hellwig
2022-11-01 11:28 ` Yu Kuai
2022-11-01 11:28 ` [dm-devel] " Yu Kuai
2022-11-01 13:18 ` Christoph Hellwig
2022-11-01 13:18 ` [dm-devel] " Christoph Hellwig
2022-11-01 13:29 ` Yu Kuai
2022-11-01 13:29 ` [dm-devel] " Yu Kuai
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