CVE-2020-29566

Name
CVE-2020-29566
Description
An issue was discovered in Xen through 4.14.x. When they require assistance from the device model, x86 HVM guests must be temporarily de-scheduled. The device model will signal Xen when it has completed its operation, via an event channel, so that the relevant vCPU is rescheduled. If the device model were to signal Xen without having actually completed the operation, the de-schedule / re-schedule cycle would repeat. If, in addition, Xen is resignalled very quickly, the re-schedule may occur before the de-schedule was fully complete, triggering a shortcut. This potentially repeating process uses ordinary recursive function calls, and thus could result in a stack overflow. A malicious or buggy stubdomain serving a HVM guest can cause Xen to crash, resulting in a Denial of Service (DoS) to the entire host. Only x86 systems are affected. Arm systems are not affected. Only x86 stubdomains serving HVM guests can exploit the vulnerability.
NVD Severity
medium
Other trackers
Mailing lists
Exploits
Forges
GitHub (code, issues), Aports (code, issues)

References

Type URI
Patch https://xenbits.xenproject.org/xsa/advisory-348.html
Third Party Advisory https://www.debian.org/security/2020/dsa-4812
Mailing List https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OBLV6L6Q24PPQ2CRFXDX4Q76KU776GKI/
Mailing List https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2C6M6S3CIMEBACH6O7V4H2VDANMO6TVA/

Match rules

CPE URI Source package Min version Max version
cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:* xen >= None <= 4.14.0

Vulnerable and fixed packages

Source package Branch Version Maintainer Status
xen 3.10-main 4.12.4-r0 None possibly vulnerable
xen 3.12-main 4.13.4-r0 Natanael Copa <ncopa@alpinelinux.org> fixed
xen 3.11-main 4.13.4-r0 Natanael Copa <ncopa@alpinelinux.org> fixed