CVE-2021-28701

Summary

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.

Affected Software

VendorProductVersion RangeStatus
Xenxenunspecified < 4.12unknown
Xenxen4.15.x < unspecifiedaffected
Xenxennext of xen-unstable < unspecifiedunaffected
Xenxen4.11.xaffected
Xenxenunspecified < 4.12unknown
Xenxen4.12.x < unspecifiedaffected
Xenxennext of 4.14.x < unspecifiedunaffected

Weaknesses

  • unknown

ADP Enrichment

CVE Program Container

Additional References

References