From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Jeffle Xu <jefflexu@linux.alibaba.com>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
Keith Busch <kbusch@kernel.org>, Sagi Grimberg <sagi@grimberg.me>,
"Wunderlich, Mark" <mark.wunderlich@intel.com>,
"Vasudevan, Anil" <anil.vasudevan@intel.com>,
linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 12/15] block: switch polling to be bio based
Date: Thu, 29 Apr 2021 09:20:28 +0200 [thread overview]
Message-ID: <20210429072028.GA3682@lst.de> (raw)
In-Reply-To: <YIjIOgYS29GvcoIm@T590>
On Wed, Apr 28, 2021 at 10:28:10AM +0800, Ming Lei wrote:
> ...
Can you please avoid the full quote?
> > + * 1) the bio is beeing initialized and bi_bdev is NULL. We can just
> > + * simply nothing in this case
> > + * 2) the bio points to a not poll enabled device. bio_poll will catch
> > + * this and return 0
> > + * 3) the bio points to a poll capable device, including but not
> > + * limited to the one that the original bio pointed to. In this
> > + * case we will call into the actual poll method and poll for I/O,
> > + * even if we don't need to, but it won't cause harm either.
> > + */
> > + rcu_read_lock();
> > + bio = READ_ONCE(kiocb->private);
> > + if (bio && bio->bi_bdev)
>
> ->bi_bdev and associated disk/request_queue/hctx/... refrerred in bio_poll()
> may have being freed now, so there is UAF risk.
the block device is RCU freed, so we are fine there. There rest OTOH
is more interesting. Let me think of a good defense using some kind
of liveness check.
next prev parent reply other threads:[~2021-04-29 7:21 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-27 16:16 switch block layer polling to a bio based model v2 Christoph Hellwig
2021-04-27 16:16 ` [PATCH 01/15] direct-io: remove blk_poll support Christoph Hellwig
2021-04-27 16:16 ` [PATCH 02/15] block: don't try to poll multi-bio I/Os in __blkdev_direct_IO Christoph Hellwig
2021-04-27 16:16 ` [PATCH 03/15] iomap: don't try to poll multi-bio I/Os in __iomap_dio_rw Christoph Hellwig
2021-04-27 16:16 ` [PATCH 04/15] blk-mq: factor out a blk_qc_to_hctx helper Christoph Hellwig
2021-04-27 16:16 ` [PATCH 05/15] blk-mq: factor out a "classic" poll helper Christoph Hellwig
2021-04-27 16:16 ` [PATCH 06/15] blk-mq: remove blk_qc_t_to_tag and blk_qc_t_is_internal Christoph Hellwig
2021-04-27 16:16 ` [PATCH 07/15] blk-mq: remove blk_qc_t_valid Christoph Hellwig
2021-04-27 16:16 ` [PATCH 08/15] io_uring: don't sleep when polling for I/O Christoph Hellwig
2021-04-27 16:16 ` [PATCH 09/15] block: rename REQ_HIPRI to REQ_POLLED Christoph Hellwig
2021-04-27 16:16 ` [PATCH 10/15] block: use SLAB_TYPESAFE_BY_RCU for the bio slab Christoph Hellwig
2021-04-27 16:16 ` [PATCH 11/15] block: define 'struct bvec_iter' as packed Christoph Hellwig
2021-04-27 16:16 ` [PATCH 12/15] block: switch polling to be bio based Christoph Hellwig
2021-04-28 2:28 ` Ming Lei
2021-04-29 7:20 ` Christoph Hellwig [this message]
2021-04-29 7:36 ` Ming Lei
2021-04-29 9:50 ` Christoph Hellwig
2021-04-29 14:42 ` Ming Lei
2021-04-27 16:16 ` [PATCH 13/15] block: add a QUEUE_FLAG_POLL_CAPABLE flag Christoph Hellwig
2021-04-27 16:16 ` [PATCH 14/15] nvme-multipath: set QUEUE_FLAG_NOWAIT Christoph Hellwig
2021-04-28 2:32 ` Ming Lei
2021-04-29 7:27 ` Christoph Hellwig
2021-04-29 7:37 ` Ming Lei
2021-04-29 9:46 ` Christoph Hellwig
2021-05-06 21:23 ` Sagi Grimberg
2021-04-27 16:16 ` [PATCH 15/15] nvme-multipath: enable polled I/O Christoph Hellwig
2021-04-28 2:36 ` Ming Lei
2021-05-12 13:15 switch block layer polling to a bio based model v3 Christoph Hellwig
2021-05-12 13:15 ` [PATCH 12/15] block: switch polling to be bio based Christoph Hellwig
2021-05-12 13:15 ` Christoph Hellwig
2021-05-12 22:03 ` Sagi Grimberg
2021-05-12 22:03 ` Sagi Grimberg
2021-05-12 22:12 ` Keith Busch
2021-05-12 22:12 ` Keith Busch
2021-05-14 2:50 ` Keith Busch
2021-05-14 2:50 ` Keith Busch
2021-05-14 16:26 ` Keith Busch
2021-05-14 16:26 ` Keith Busch
2021-05-14 16:28 ` Christoph Hellwig
2021-05-14 16:28 ` Christoph Hellwig
2021-05-13 1:26 ` Ming Lei
2021-05-13 1:26 ` Ming Lei
2021-05-13 1:23 ` Ming Lei
2021-05-13 1:23 ` Ming Lei
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