During Xenstore live update the state record for a Xenstore watch with
specified watch depth is written with two bytes missing. This results
in an inconsistent state when reading the state back in the new Xenstore,
causing a crash of Xenstore or wrong Xenstore data.
Only systems running Xen 4.22 are vulnerable. Systems running Xen 4.21
or older are not vulnerable.
Only systems running C xenstore either as daemon or as stubdom are
vulnerable. Systems running oxenstored are not vulnerable.
Not doing a live update of Xenstore avoids the vulnerability.
Switching to oxenstored avoids the vulnerability.