Allowing arbitrary extent_order input values for XENMEM_decrease_reservation,
XENMEM_populate_physmap, and XENMEM_exchange can cause arbitrarily long time
being spent in loops without allowing vital other code to get a chance to
execute. This may also cause inconsistent state resulting at the completion
of these hypercalls.
A malicious guest administrator can cause Xen to hang.
Versions of Xen that do not support supporting Populate-on-Demand may
only be theoretically affected.
Acknowledgements:
Red Hat would like to thank the Xen project for reporting this issue.
Statement:
This issue did affect the versions of the kernel-xen package as shipped with Red Hat Enterprise Linux 5.
This issue did not affect Red Hat Enterprise Linux 6 and Red Hat Enterprise MRG as we did not have support for Xen hypervisor.
Allowing arbitrary extent_order input values for XENMEM_decrease_reservation, XENMEM_populate_physmap, and XENMEM_exchange can cause arbitrarily long time being spent in loops without allowing vital other code to get a chance to execute. This may also cause inconsistent state resulting at the completion of these hypercalls. A malicious guest administrator can cause Xen to hang. Versions of Xen that do not support supporting Populate-on-Demand may only be theoretically affected. Acknowledgements: Red Hat would like to thank the Xen project for reporting this issue.