Re: [Qemu-devel] [Qemu-stable] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer

[Peter Lieven]

Am 13.05.2015 um 21:52 schrieb Markus Armbruster:
> Peter Lieven <address@hidden> writes:
>
>> Am 13.05.2015 um 21:09 schrieb Stefan Priebe:
>>> Am 13.05.2015 um 21:05 schrieb Stefan Weil:
>>>> Am 13.05.2015 um 20:59 schrieb Stefan Priebe:
>>>>> Am 13.05.2015 um 20:51 schrieb Stefan Weil:
>>>>>> Hi,
>>>>>>
>>>>>> I just noticed this patch because my provider told me that my KVM based
>>>>>> server
>>>>>> needs a reboot because of a CVE (see this German news:
>>>>>> http://www.heise.de/newsticker/meldung/Venom-Schwachstelle-Aus-Hypervisor-ausbrechen-und-VMs-ausspionieren-2649614.html)
>>>>>>
>>>>> Isn't a live migration to a fixed version enough instead of a reboot?
>>>>>
>>>>> Stefan
>>>> Good point. A live migration would be sufficient - if there are no bugs
>>>> in QEMU's live migration.
>>> just migrating all our customer machines and wanted to be sure that
>>> live migration is enough.
>> Just to confirm: If Qemu is started with -nodefaults and there is no
>> fdc configuration the system is not affected by this CVE?
> Not true.  The FD controller is still there.  It has no drives attached
> then, but is vulnerable all the same.

Are you sure? With -nodefaults the hmp command 'info block' returns nothing and
the guest sees no floppy drive.

Without -nodefaults I indeed see floppy0 and I have /dev/fd0 in the guest 
respectively.

Peter