This issue does not affect the version of the kernel package as shipped with Kylin Enterprise Linux 5, 6 and Kylin Enterprise MRG 2.
This issue affects the versions of Linux kernel as shipped with Kylin Enterprise Linux 7. Future kernel updates for Kylin Enterprise Linux 7 may address this issue.
Note: Impact on Kylin Enterprise Linux 7 kernel is limited, as it requires that nested virtualization feature is enabled on a system. Nested Virtualization feature is available only as - Technology Preview.
** RESERVED ** This candidate has been reserved by an organization or individual that will use it when announcing a new security problem. When the candidate has been publicized, the details for this candidate will be provided.
A use-after-free vulnerability was found in the way the Linux kernel's KVM hypervisor emulates a preemption timer for L2 guests when nested (=1) virtualization is enabled. This high resolution timer(hrtimer) runs when a L2 guest is active. After VM exit, the sync_vmcs12() timer object is stopped. The use-after-free occurs if the timer object is freed before calling sync_vmcs12() routine. A guest user/process could use this flaw to crash the host kernel resulting in a denial of service or, potentially, gain privileged access to a system.