| Message ID | 20170518102808.30046-1-famz@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 18/05/2017 12:28, Fam Zheng wrote: > 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. Queued this for now. Paolo
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); }
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(+)