After a suspend/resume cycle of a Linux guest (e.g. via "virsh dompmsuspend"/ "virsh dompmwakeup") a malicious network backend can crash the guest via a NULL-pointer dereference in the guest's xen-netfront driver.

During the resume operation the xen-netfront driver will release some data structures used for communication with the backend, in order to reallocate these data structures with possibly different parameters specified by the backend. If the backend is triggering a network device removal in the guest before any network I/O has happened, the NULL-pointer dereference may happen, causing a crash of the guest.