CVE-2019-7221

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.

This issue does not affect the version of the kernel package as shipped with Red Hat Enterprise Linux 5, 6 and Red Hat Enterprise MRG 2.

This issue affects the versions of Linux kernel as shipped with Red Hat Enterprise Linux 7. Future kernel updates for Red Hat Enterprise Linux 7 may address this issue.

Note: Impact on Red Hat 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.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.