CVE-2022-50227

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86/xen: Initialize Xen timer only once

Add a check for existing xen timers before initializing a new one.

Currently kvm_xen_init_timer() is called on every KVM_XEN_VCPU_ATTR_TYPE_TIMER, which is causing the following ODEBUG crash when vcpu->arch.xen.timer is already set.

ODEBUG: init active (active state 0) object type: hrtimer hint: xen_timer_callbac0 RIP: 0010:debug_print_object+0x16e/0x250 lib/debugobjects.c:502 Call Trace: __debug_object_init debug_hrtimer_init debug_init hrtimer_init kvm_xen_init_timer kvm_xen_vcpu_set_attr kvm_arch_vcpu_ioctl kvm_vcpu_ioctl vfs_ioctl

This vulnerability is rated as having a Moderate impact for Red Hat Enterprise Linux because exploitation requires local access with privileges to interact directly with the KVM hypervisor subsystem, limiting the blast radius to virtualization hosts. In standard Red Hat environments, access to KVM device interfaces is restricted to privileged accounts or virtualization processes. The flaw is triggered only when managing virtual machines that utilize Xen emulation, specifically when repeatedly invoking timer attribute configuration ioctls on an active vCPU. Systems that do not run KVM workloads or do not employ Xen guest emulation are not exposed to this issue.

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.