In the Linux kernel, the following vulnerability has been resolved:
kvm: LAPIC: Restore guard to prevent illegal APIC register access
Per the SDM, "any access that touches bytes 4 through 15 of an APIC register may cause undefined behavior and must not be executed." Worse, such an access in kvmlapicreg_read can result in a leak of kernel stack contents. Prior to commit 01402cf81051 ("kvm: LAPIC: write down valid APIC registers"), such an access was explicitly disallowed. Restore the guard that was removed in that commit.