linux-kernel - Re: usercopy whitelist woe in scsi_sense

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Message-ID: <CAGXu5j+ZmgfqdoT_zPZ4qLCdMfjaaGxRCyz8c8ecp=39zQfw2w@mail.gmail.com>
Date:   Tue, 10 Apr 2018 20:13:01 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Oleksandr Natalenko <oleksandr@...alenko.name>
Cc:     David Windsor <dave@...lcore.net>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Hannes Reinecke <hare@...e.com>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        linux-block@...r.kernel.org, paolo.valente@...aro.org
Subject: Re: usercopy whitelist woe in scsi_sense_cache

On Tue, Apr 10, 2018 at 10:16 AM, Oleksandr Natalenko
<oleksandr@...alenko.name> wrote:
> Hi, Kees, Paolo et al.
>
> 10.04.2018 08:53, Kees Cook wrote:
>>
>> Unfortunately I only had a single hang with no dumps. I haven't been
>> able to reproduce it since. :(
>
>
> For your convenience I've prepared a VM that contains a reproducer.

Awesome. :)

> Under the /root folder there is a reproducer script (reproducer.sh). It does
> trivial things like enabling sysrq, opening LUKS device, mounting a volume,
> running a background I/O (this is an important part, actually, since I
> wasn't able to trigger the issue without the background I/O) and, finally,
> running the smartctl in a loop. If you are lucky, within a minute or two
> you'll get the first warning followed shortly by subsequent bugs and I/O
> stall (htop is pre-installed for your convenience too).

Yup!

[   27.729498] Bad or missing usercopy whitelist? Kernel memory
exposure attempt detected from SLUB object 'scsi_sense_cache' (offset
76, size 22)!

I'll see about booting with my own kernels, etc, and try to narrow this down. :)

-Kees

-- 
Kees Cook
Pixel Security