The handler for XEN_DOMCTL_gettscinfo failed to initialize a padding
field subsequently copied to guest memory.
A similar leak existed in XEN_SYSCTL_getdomaininfolist, which is being
addressed here regardless of that operation being declared unsafe for
disaggregation by XSA-77.
Malicious or buggy stub domain kernels or tool stacks otherwise living
outside of Domain0 may be able to read sensitive data relating to the
hypervisor or other guests not under the control of that domain.