CVE-2021-28701

Description

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.

References

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

https://lists.fedoraproject.org/archives/list/[email protected]/message/L4MI3MQAPGILCLXBGQWPZHGE3ALSO4ZU/

https://lists.fedoraproject.org/archives/list/[email protected]/message/CEHZLIR5DFYYQBH55AERWHLO54OFU42C/

https://www.debian.org/security/2021/dsa-4977

https://lists.fedoraproject.org/archives/list/[email protected]/message/3HEHUIUWSSMCQGQY3GWX4J2SZGYP5W2Z/

https://security.gentoo.org/glsa/202208-23

Details

Risk Information

CVSS v2

CVSS v3