On Thu, Aug 11, 2016 at 09:18:12AM +0200, Gaudenz Steinlin wrote: > > [ Please CC me on replies as I'm not subscribed to this list. ] > > Hi > > The Fix for CVE-2016-5403 (virtio: error out if guest exceeds virtqueue > size)[1] causes qemu to exit(1) after migration or restart from a saved > state if memory statistics are enabled in libvirt. Qemu exits after > printing "qemu-system-x86_64: Virtqueue size exceeded". > > I experienced this problem with the latest security update in Ubuntu > Trusty (14.04) which cherry-picked this fix. If you think that the > latest upstream version is not affected I can try this too. I only > tested with VM started through libvirt. If someone tells me how to > enable memory statistics with plain qemu without libvirt I can test this > too. My guess would be that this does not make a difference. > > I discovered this bug because OpenStack Nova enables memory statistics > by default since the Juno release. After the QEMU upgrade to the latest > version in Ubuntu VMs were suddenly shutoff after migration. > > Steps to reproduce: > 1. Create a VM with libvirt which contains a memory balloon device > defined like this: > <memballoon model='virtio'> > <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> > <stats period='10'/> > </memballoon> > > 2. Start the VM and let the Linux kernel boot (bug does not appear if > the kernel is not yet booted, eg. while in the PXE boot phase) > 3. Issue a managedsave > 4. Start the VM again > 5. The VM is restored and "crashes" right after it starts running again. > 6. You can find the qemu output "qemu-system-x86_64: Virtqueue size > exceeded" in the log at /var/log/libvirt/vmname.log
I couldn't reproduce this with qemu.git/master (28b874429ba) and a RHEL 7.2 guest. Which guest distro and kernel version are you using? Are you doing anything that might cause virtio-balloon activity? Stefan
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