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.
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
Source: MITRE
Published: 2021-09-08
Updated: 2022-10-28
Type: CWE-362
Base Score: 4.4
Vector: AV:L/AC:M/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 3.4
Severity: MEDIUM
Base Score: 7.8
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Impact Score: 6
Exploitability Score: 1.1
Severity: HIGH