From: Hannes Reinecke <hare@suse.de>
To: Minchan Kim <minchan@kernel.org>,
Johannes Thumshirn <jthumshirn@suse.de>
Cc: Jens Axboe <axboe@fb.com>, Nitin Gupta <ngupta@vflare.org>,
Christoph Hellwig <hch@lst.de>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
yizhan@redhat.com,
Linux Block Layer Mailinglist <linux-block@vger.kernel.org>,
Linux Kernel Mailinglist <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] zram: set physical queue limits to avoid array out of bounds accesses
Date: Tue, 7 Mar 2017 08:00:30 +0100 [thread overview]
Message-ID: <95c31a93-32cd-ad06-6cc0-e11b42ec2f68@suse.de> (raw)
In-Reply-To: <20170307052242.GA29458@bbox>
On 03/07/2017 06:22 AM, Minchan Kim wrote:
> Hello Johannes,
>
> On Mon, Mar 06, 2017 at 11:23:35AM +0100, Johannes Thumshirn wrote:
>> zram can handle at most SECTORS_PER_PAGE sectors in a bio's bvec. When using
>> the NVMe over Fabrics loopback target which potentially sends a huge bulk of
>> pages attached to the bio's bvec this results in a kernel panic because of
>> array out of bounds accesses in zram_decompress_page().
>
> First of all, thanks for the report and fix up!
> Unfortunately, I'm not familiar with that interface of block layer.
>
> It seems this is a material for stable so I want to understand it clear.
> Could you say more specific things to educate me?
>
> What scenario/When/How it is problem? It will help for me to understand!
>
The problem is that zram as it currently stands can only handle bios
where each bvec contains a single page (or, to be precise, a chunk of
data with a length of a page).
This is not an automatic guarantee from the block layer (who is free to
send us bios with arbitrary-sized bvecs), so we need to set the queue
limits to ensure that.
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: F. Imend�rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG N�rnberg)
next prev parent reply other threads:[~2017-03-07 7:34 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-06 10:23 [PATCH] zram: set physical queue limits to avoid array out of bounds accesses Johannes Thumshirn
2017-03-06 10:25 ` Hannes Reinecke
2017-03-06 10:45 ` Sergey Senozhatsky
2017-03-06 15:21 ` Jens Axboe
2017-03-06 20:18 ` Andrew Morton
2017-03-06 20:19 ` Jens Axboe
2017-03-07 5:22 ` Minchan Kim
2017-03-07 7:00 ` Hannes Reinecke [this message]
2017-03-07 7:23 ` Minchan Kim
2017-03-07 7:48 ` Hannes Reinecke
2017-03-07 8:55 ` Minchan Kim
2017-03-07 9:51 ` Johannes Thumshirn
2017-03-08 5:11 ` Minchan Kim
2017-03-08 7:58 ` Johannes Thumshirn
2017-03-09 5:28 ` Minchan Kim
2017-03-30 15:08 ` Minchan Kim
2017-03-30 15:35 ` Jens Axboe
2017-03-30 23:45 ` Minchan Kim
2017-03-31 1:38 ` Jens Axboe
2017-04-03 5:11 ` Minchan Kim
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