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.
https://xenbits.xenproject.org/xsa/advisory-394.txt
http://www.openwall.com/lists/oss-security/2022/01/25/3
Source: MITRE
Published: 2022-01-25
Updated: 2022-08-19
Type: CWE-191
Base Score: 2.1
Vector: AV:L/AC:L/Au:N/C:N/I:N/A:P
Impact Score: 2.9
Exploitability Score: 3.9
Severity: LOW
Base Score: 5.5
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 1.8
Severity: MEDIUM