Re: Commit d9e7972619334656 breaks KVM's virtio-rng-pci

[Kees Cook]

On Sun, Jul 20, 2014 at 11:32 AM, Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote:
> Hi Kees,
>
>>> the commit d9e7972619334656 ends up being responsible that using "-device virtio-rng-pci" in KVM no longer works.
>>>
>>>        From: Kees Cook <keescook@xxxxxxxxxxxx>
>>>        Date: Mon, 3 Mar 2014 15:51:48 -0800
>>>        Subject: [PATCH] hwrng: add randomness to system from rng sources
>>>
>>>        When bringing a new RNG source online, it seems like it would make sense
>>>        to use some of its bytes to make the system entropy pool more random,
>>>        as done with all sorts of other devices that contain per-device or
>>>        per-boot differences.
>>>
>>> When providing "-device virtio-rng-pci" to a kernel with the above commit, the kernel never finishes booting. It just stops. My guess it is waiting for some magic entropy to appear.
>>>
>>> Maybe this is something that should be fixed in virtio-rng driver instead of reverting this patch, but I leave this to the experts in this area.
>>
>> Yup, this has already been handled. See various threads around:
>> https://lkml.org/lkml/2014/7/5/14
>
> I bisected 3.16-rc5 and it was not yet fixed there. It seems the fixes got merged less than 48 hours ago. Which means I just missed them. Tried with HEAD now and all looks good.

Great! Thanks for testing.

-Kees

-- 
Kees Cook
Chrome OS Security
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