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.
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
| Link | Tags |
|---|---|
| https://xenbits.xenproject.org/xsa/advisory-394.txt | patch vendor advisory |
| http://www.openwall.com/lists/oss-security/2022/01/25/3 | third party advisory mailing list |
| https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OMR6UBGJW6JKND7IILGQ2CU35EQPF3E3/ | vendor advisory |
| https://www.debian.org/security/2022/dsa-5117 | third party advisory vendor advisory |
| https://security.gentoo.org/glsa/202208-23 | third party advisory vendor advisory |