An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions are vulnerable in principle. Whether versions 4.3 and older are vulnerable depends on underlying hardware characteristics.
NOTE: The following CVSS v3.0 metrics and score provided are preliminary and subject to review.
|Base Score:||5.5||Base Metrics:||AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H|
|Access Vector:||Local network||Attack Complexity:||Low|
|Privileges Required:||Low||User Interaction:||None|
|Integrity Impact:||None||Availability Impact:||High|
|Oracle VM version 3 (xen)||OVMSA-2021-0014||2021-04-27|
|Oracle VM version 3.4 (xen)||OVMSA-2021-0014||2021-04-27|
This page is generated automatically and has not been checked for errors or omissions. For clarification or corrections please contact the Oracle Linux ULN team