MMU update operations targeting page tables are intended to be used on
PV guests only. The lack of a respective check made it possible for
such operations to access certain function pointers which remain NULL
when the target guest is using Hardware Assisted Paging (HAP).
Malicious or buggy stub domain kernels or tool stacks otherwise living
outside of Domain0 can mount a denial of service attack which, if
successful, can affect the whole system.
Red Hat would like to thank the Xen for reporting this issue.
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 1165205]