CVE-2021-3714

Отчет

This issue affects the versions of the Linux Kernel as shipped with Red Hat Enterprise Linux 6,7 and 8. Red Hat Product Security has rated this issue as having Moderate security impact. Additionally a workaround is available. A future update may address this issue. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.

Меры по смягчению последствий

The mitigation shown below has a potentially significant impact on system performance and stability. It should be carefully tested prior to deployment:

• Deactivation of memory deduplication Deactivating memory deduplication will effectively mitigate all attack vectors. This measure unfortunately eliminates all the highly appreciated benefits of memory deduplication, namely the increase of operational cost-effectiveness through inter-VM memory sharing. This will cause an increase in the amount of memory required and in some situations may adversely impact performance (e.g. due to slower swap space being used). It is recommended that customers test this workaround before using it in production. See https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/virtualization_tuning_and_optimization_guide/sect-ksm-deactivating_ksm for how to disable KSM from Red Hat Enterprise Linux 6 and newer.
• Disabling services and firewall rules. The attack uses the response time of services on the system. By limiting access to services an attacker must connect to the service to successful carry out the exploit. Reducing the number of systems that are allowed to connect to the service will prevent an attack from working when launched outside an allowed ranges. While this does not prevent an attack from working, it will reduce the amount of systems that an attacker can launch an attack from.