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From: "Sebastian Herbszt" <herbszt@gmx.de>
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Subject: Re: [Qemu-devel] Re: POST failure (loop) with isapc and seabios
Date: Sun, 22 Nov 2009 22:15:59 +0100
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To: Kevin O'Connor <kevin@koconnor.net>, Gleb Natapov <gleb@redhat.com>
Cc: qemu-devel@nongnu.org

Kevin O'Connor wrote:
>> On Sun, Nov 22, 2009 at 04:31:24PM +0100, Sebastian Herbszt wrote:
>> > Bad things could happen if someone modifies the BIOS because it's unprotected
>> > (e.g. VM crash).
> 
> I'm not sure why modification of the BIOS would cause a VM crash.  If
> this is true, then a malicious guest could unlock the ram and write to
> it for the same effect.

On Linux only root can unlock the memory. If the memory is unlocked and
a user manages to overwrite the BIOS, the VM will crash on next "reboot"
or system_reset. If the OS is using the BIOS interfaces more often, e.g. INT 13h,
bad things could happen earlier.

- Sebastian