linux-kernel - Re: sudo x86info -a => kernel BUG at mm/usercopy.c:78!

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Date:   Fri, 31 Mar 2017 08:44:43 +0300
From:   Tommi Rantala <tommi.t.rantala@...ia.com>
To:     Laura Abbott <labbott@...hat.com>,
        Kees Cook <keescook@...omium.org>
CC:     Linux-MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Eric Biggers <ebiggers@...gle.com>,
        Dave Jones <davej@...emonkey.org.uk>
Subject: Re: sudo x86info -a => kernel BUG at mm/usercopy.c:78!

On 30.03.2017 20:44, Laura Abbott wrote:
> On 03/30/2017 10:37 AM, Kees Cook wrote:
>>
>> Reads out of /dev/mem should be restricted to non-RAM on Fedora, yes?
>>
>> Tommi, do your kernels have CONFIG_STRICT_DEVMEM=y ?
>>
>> -Kees
>>
>
> CONFIG_STRICT_DEVMEM should be on in all Fedora kernels.

Yes, the fedora kernels do have it enabled:

   $ grep STRICT_DEVMEM /boot/config-4.9.14-200.fc25.x86_64
   CONFIG_STRICT_DEVMEM=y
   CONFIG_IO_STRICT_DEVMEM=y

But I do not have it in my own build:

   $ grep STRICT_DEVMEM .config
   # CONFIG_STRICT_DEVMEM is not set

-Tommi