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From: Bart Van Assche <bvanassche@acm.org>
To: Damien Le Moal <Damien.LeMoal@wdc.com>,
	Alexander Potapenko <glider@google.com>
Cc: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
	Jens Axboe <axboe@kernel.dk>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	Willem de Bruijn <willemb@google.com>,
	Dmitriy Vyukov <dvyukov@google.com>
Subject: Re: null_handle_cmd() doesn't initialize data when reading
Date: Mon, 11 May 2020 19:43:50 -0700	[thread overview]
Message-ID: <b90e0030-c0fa-7e7e-ea17-137d49293f54@acm.org> (raw)
In-Reply-To: <BY5PR04MB690045ED7665BF98A2EA7ED3E7BE0@BY5PR04MB6900.namprd04.prod.outlook.com>

On 2020-05-11 18:42, Damien Le Moal wrote:
> The patch looks good to me. However, I have one concern regarding the
> performance impact of this. When nullblk is used to benchmark the block IO stack
> overhead, doing this zeroing unconditionally will likely significantly impact
> measured performance. So may be this zeroing feature should be driven by a
> modprobe/configfs option ? Doing so, we can keep it off by default, preserving
> performance, and turn it on when needed as in Alexander use case.
> 
> Thoughts ?

Hi Damien,

Does the current implementation of null_blk allow one process to access
data that was generated by another process? If so, does that behavior
count as a security bug?

I am aware of the performance impact of the patch attached to my
previous email. I have not made the zeroing behavior optional because
I'm concerned about the security implications of doing that.

Bart.



  reply	other threads:[~2020-05-12  2:43 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-15 10:16 null_handle_cmd() doesn't initialize data when reading Alexander Potapenko
2019-11-20 23:12 ` Jens Axboe
2019-11-22 11:58   ` Alexander Potapenko
2019-11-25  4:01     ` Chaitanya Kulkarni
2020-05-10 10:03       ` Alexander Potapenko
2020-05-10 16:20         ` Bart Van Assche
2020-05-11 12:58           ` Alexander Potapenko
2020-05-11 13:01             ` Damien Le Moal
2020-05-11 13:09               ` Alexander Potapenko
2020-05-11 23:18             ` Bart Van Assche
2020-05-12  1:25               ` Bart Van Assche
2020-05-12  1:42                 ` Damien Le Moal
2020-05-12  2:43                   ` Bart Van Assche [this message]
2020-05-12  3:23                     ` Damien Le Moal

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