Consider the following nested setup: An L1 host uses some virtio device
(e.g. virtio-keyboard) for the L2 guest, and this L2 guest passes this
device through to the L3 guest. Since the L3 guest sees a virtio device,
it might send virtio notifications to the QEMU in L2 for that device.
But since the QEMU in L2 defined this device as vfio-ccw, the function
handle_virtio_ccw_notify() cannot handle this and crashes: It calls
virtio_ccw_get_vdev() that casts sch->driver_data into a VirtioCcwDevice,
but since "sch" belongs to a vfio-ccw device, that driver_data rather
points to a CcwDevice instead. So as soon as QEMU tries to use some
VirtioCcwDevice specific data from that device, we've lost.
We must not take virtio notifications for such devices. Thus fix the
issue by adding a check to the handle_virtio_ccw_notify() handler to
refuse all devices that are not our own virtio devices. Like in the
other branches that detect wrong settings, we return -EINVAL from the
function, which will later be placed in GPR2 to inform the guest about
the error.
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Tested-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20251118174047.73103-1-thuth@redhat.com>
e5cb62e7b6