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.
Advisories
Source ID Title
Debian DSA Debian DSA DSA-4977-1 xen security update
EUVD EUVD EUVD-2021-15358 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.
Fixes

Solution

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Workaround

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cve-icon MITRE

Status: PUBLISHED

Assigner: XEN

Published:

Updated: 2024-08-03T21:47:33.200Z

Reserved: 2021-03-18T00:00:00

Link: CVE-2021-28701

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2021-09-08T14:15:08.547

Modified: 2024-11-21T06:00:10.450

Link: CVE-2021-28701

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

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Weaknesses