CVE-2022-23034

A PV guest could DoS Xen while unmapping a grant To address XSA-380,
reference counting was introduced for grant mappings for the case where a
PV guest would have the IOMMU enabled. PV guests can request two forms of
mappings. When both are in use for any individual mapping, unmapping of
such a mapping can be requested in two steps. The reference count for such
a mapping would then mistakenly be decremented twice. Underflow of the
counters gets detected, resulting in the triggering of a hypervisor bug
check.

Notes