An issue was discovered in Xen through 4.14.x. There are missing memory barriers when accessing/allocating an event channel. Event channels control structures can be accessed lockless as long as the port is considered to be valid. Such a sequence is missing an appropriate memory barrier (e.g., smp_*mb()) to prevent both the compiler and CPU from re-ordering access. A malicious guest may be able to cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded. Systems running all versions of Xen are affected. Whether a system is vulnerable will depend on the CPU and compiler used to build Xen. For all systems, the presence and the scope of the vulnerability depend on the precise re-ordering performed by the compiler used to build Xen. We have not been able to survey compilers; consequently we cannot say which compiler(s) might produce vulnerable code (with which code generation options). GCC documentation clearly suggests that re-ordering is possible. Arm systems will also be vulnerable if the CPU is able to re-order memory access. Please consult your CPU vendor. x86 systems are only vulnerable if a compiler performs re-ordering.
NOTE: The following CVSS v3.0 metrics and score provided are preliminary and subject to review.
|Base Score:||7.8||Base Metrics:||AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H|
|Access Vector:||Local network||Attack Complexity:||Low|
|Privileges Required:||Low||User Interaction:||None|
|Integrity Impact:||High||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