CVE-2026-64604

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

KVM: VMX: Grab vmcs12 on CR8 interception update iff vCPU is in guest mode

When updating CR8 intercepts, get vmcs12 if and only if the vCPU is in guest mode so that a future change can have update CR8 intercepts during vCPU creation, without running afoul of get_vmcs12()'s lockdep assertion.

------------[ cut here ]------------ debuglocks && !(lockisheld(&(&vcpu->mutex)->depmap) || !refcountread(&vcpu->kvm->userscount)) WARNING: arch/x86/kvm/vmx/nested.h:61 at getvmcs12 arch/x86/kvm/vmx/nested.h:60 [inline], CPU#0: syz.2.19/5879 WARNING: arch/x86/kvm/vmx/nested.h:61 at vmxupdatecr8intercept+0x3de/0x4e0 arch/x86/kvm/vmx/vmx.c:6879, CPU#0: syz.2.19/5879 Modules linked in: CPU: 0 UID: 0 PID: 5879 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:getvmcs12 arch/x86/kvm/vmx/nested.h:60 [inline] RIP: 0010:vmxupdatecr8intercept+0x3de/0x4e0 arch/x86/kvm/vmx/vmx.c:6879 Call Trace: <TASK> apicupdateppr arch/x86/kvm/lapic.c:984 [inline] kvmlapicreset+0x1c24/0x2980 arch/x86/kvm/lapic.c:3023 kvmvcpureset+0x44c/0x1bf0 arch/x86/kvm/x86.c:12986 kvmarchvcpucreate+0x746/0x8b0 arch/x86/kvm/x86.c:12847 kvmvmioctlcreatevcpu+0x428/0x930 virt/kvm/kvmmain.c:4201 kvmvmioctl+0x893/0xd50 virt/kvm/kvmmain.c:5159 vfsioctl fs/ioctl.c:51 [inline] __dosysioctl fs/ioctl.c:597 [inline] __sesysioctl+0xfc/0x170 fs/ioctl.c:583 dosyscallx64 arch/x86/entry/syscall64.c:63 [inline] dosyscall64+0x174/0x580 arch/x86/entry/syscall64.c:94 entrySYSCALL64afterhwframe+0x77/0x7f </TASK>

No functional change intended.