This matches the qbus_set_hotplug_handler in realize and is important to
release the final reference to the embedded VirtIODevice so that it is
properly finalized.
A use-after-free is fixed with this patch, indirectly:
virtio_device_instance_finalize wasn't called at hot-unplug, and the
vdev->listener would be a dangling pointer in the global and the per
address space listener list. See also RHBZ 1449031.
Thanks to Paolo for explaining the reference counting.
Cc: qemu-stable@nongnu.org
Signed-off-by: Fam Zheng <famz@redhat.com>
---
Like suggested by Paolo, it seems to make sense to do this clean up in
bus_unparent, but given how confused I got when working on this bug, I'm
not confident in my reasoning about the ref count balance in other
callers.
---
hw/scsi/virtio-scsi.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 46a3e3f..f46f06d 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -918,6 +918,9 @@ void virtio_scsi_common_unrealize(DeviceState *dev, Error **errp)
static void virtio_scsi_device_unrealize(DeviceState *dev, Error **errp)
{
+ VirtIOSCSI *s = VIRTIO_SCSI(dev);
+
+ qbus_set_hotplug_handler(BUS(&s->bus), NULL, &error_abort);
virtio_scsi_common_unrealize(dev, errp);
}
--
2.9.3