CVE-2021-28701

Published: 08 September 2021

Another race in XENMAPSPACE_grant_table handling Guests are permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, are de-allocated when a guest switches (back) from v2 to v1. Freeing such pages requires that the hypervisor enforce that no parallel request can result in the addition of a mapping of such a page to a guest. That enforcement was missing, allowing guests to retain access to pages that were freed and perhaps re-used for other purposes. Unfortunately, when XSA-379 was being prepared, this similar issue was not noticed.

Priority

Medium

CVSS 3 base score: 7.8

Status

Notes

hypervisor packages are in universe. For
issues in the hypervisor, add appropriate
tags to each section, ex:
Tags_xen: universe-binary

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-28701
• https://xenbits.xen.org/xsa/advisory-384.html
• https://xenbits.xenproject.org/xsa/advisory-384.txt
• http://xenbits.xen.org/xsa/advisory-384.html
• http://www.openwall.com/lists/oss-security/2021/09/08/2
• NVD
• Launchpad
• Debian