The implementation in Xen of the HVMOP_set_mem_type HVM control operations attempts to exclude transitioning a page from an inappropriate memory type. However, only an inadequate subset of memory types is excluded. There are certain other types that don't correspond to a particular valid page, whose page table translation can be inappropriately changed (by HVMOP_set_mem_type) from not-present (due to the lack of valid memory page) to present. If this occurs, an invalid translation will be established. A malicious administrator of a domain privileged with regard to an HVM guest can cause Xen to crash leading to a Denial of Service. Arbitrary code execution, and therefore privilege escalation, cannot be entirely excluded: On a system with a RAM page present immediately below the 52-bit address boundary, this would be possible. However, we are not aware of any systems with such a memory layout. Acknowledgements: Red Hat would like to thank the Xen project for reporting this issue.
Statement: Not vulnerable. This issue did not affect the versions of the kernel-xen package as shipped with Red Hat Enterprise Linux 5.
Created xen tracking bugs for this issue: Affects: fedora-all [bug 1093315]