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Subject: Re: sudo x86info -a => kernel BUG at mm/usercopy.c:78!
References: <d928849c-e7c3-6b81-e551-a39fa976f341@nokia.com>
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From: Tommi Rantala <tommi.t.rantala@nokia.com>
Message-ID: <bc2fa666-cbfb-e78d-39f7-be7ab66bf34d@nokia.com>
Date: Fri, 31 Mar 2017 08:44:43 +0300
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Sender: owner-linux-mm@kvack.org
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To: Laura Abbott <labbott@redhat.com>, Kees Cook <keescook@chromium.org>
Cc: Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>, Josh Poimboeuf <jpoimboe@redhat.com>, Mark Rutland <mark.rutland@arm.com>, Eric Biggers <ebiggers@google.com>, Dave Jones <davej@codemonkey.org.uk>

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

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