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Date: Mon, 24 Feb 2025 14:02:55 -0700
From: Keith Busch <kbusch@kernel.org>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: Keith Busch <kbusch@meta.com>, ming.lei@redhat.com, axboe@kernel.dk,
	linux-block@vger.kernel.org, io-uring@vger.kernel.org,
	bernd@bsbernd.com, csander@purestorage.com
Subject: Re: [PATCHv4 3/5] ublk: zc register/unregister bvec
Message-ID: <Z7zef3Ty42PbXxkT@kbusch-mbp>
References: <20250218224229.837848-1-kbusch@meta.com>
 <20250218224229.837848-4-kbusch@meta.com>
 <a636d5fa-1c60-410a-a876-52859df7277a@gmail.com>
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In-Reply-To: <a636d5fa-1c60-410a-a876-52859df7277a@gmail.com>

On Thu, Feb 20, 2025 at 11:11:59AM +0000, Pavel Begunkov wrote:
> On 2/18/25 22:42, Keith Busch wrote:
> > +static int ublk_unregister_io_buf(struct io_uring_cmd *cmd,
> > +				  struct ublk_queue *ubq, int tag,
> > +				  const struct ublksrv_io_cmd *ub_cmd,
> > +				  unsigned int issue_flags)
> > +{
> > +	struct io_ring_ctx *ctx = cmd_to_io_kiocb(cmd)->ctx;
> > +	struct ublk_device *ub = cmd->file->private_data;
> > +	int index = (int)ub_cmd->addr;
> > +	struct ublk_rq_data *data;
> > +	struct request *req;
> > +
> > +	if (!ub)
> > +		return -EPERM;
> > +
> > +	req = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], tag);
> 
> Shouldn't there some speculation sanitisation for the tag as well?
> Looks like a user passed value directly indexing an array.

There are no other array speculation defenses here, so looks like a
pre-existing issue. I'll send something to address that separate from
this series.