In the Linux kernel, the following vulnerability has been resolved: KVM: VMX: Always clear vmx->fail on emulation_required Revert a relatively recent change that set vmx->fail if the vCPU is in L2 and emulation_required is true, as that behavior is completely bogus. Setting vmx->fail and synthesizing a VM-Exit is contradictory and wrong: (a) it's impossible to have both a VM-Fail and VM-Exit (b) vmcs.EXIT_REASON is not modified on VM-Fail (c) emulation_required refers to guest state and guest state checks are always VM-Exits, not VM-Fails. For KVM specifically, emulation_required is handled before nested exits in __vmx_handle_exit(), thus setting vmx->fail has no immediate effect, i.e. KVM calls into handle_invalid_guest_state() and vmx->fail is ignored. Setting vmx->fail can ultimately result in a WARN in nested_vmx_vmexit() firing when tearing down the VM as KVM never expects vmx->fail to be set when L2 is active, KVM always reflects those errors into L1. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 21158 at arch/x86/kvm/vmx/nested.c:4548 nested_vmx_vmexit+0x16bd/0x17e0 arch/x86/kvm/vmx/nested.c:4547 Modules linked in: CPU: 0 PID: 21158 Comm: syz-executor.1 Not tainted 5.16.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:nested_vmx_vmexit+0x16bd/0x17e0 arch/x86/kvm/vmx/nested.c:4547 Code: <0f> 0b e9 2e f8 ff ff e8 57 b3 5d 00 0f 0b e9 00 f1 ff ff 89 e9 80 Call Trace: vmx_leave_nested arch/x86/kvm/vmx/nested.c:6220 [inline] nested_vmx_free_vcpu+0x83/0xc0 arch/x86/kvm/vmx/nested.c:330 vmx_free_vcpu+0x11f/0x2a0 arch/x86/kvm/vmx/vmx.c:6799 kvm_arch_vcpu_destroy+0x6b/0x240 arch/x86/kvm/x86.c:10989 kvm_vcpu_destroy+0x29/0x90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:441 kvm_free_vcpus arch/x86/kvm/x86.c:11426 [inline] kvm_arch_destroy_vm+0x3ef/0x6b0 arch/x86/kvm/x86.c:11545 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1189 [inline] kvm_put_kvm+0x751/0xe40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1220 kvm_vcpu_release+0x53/0x60 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3489 __fput+0x3fc/0x870 fs/file_table.c:280 task_work_run+0x146/0x1c0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:32 [inline] do_exit+0x705/0x24f0 kernel/exit.c:832 do_group_exit+0x168/0x2d0 kernel/exit.c:929 get_signal+0x1740/0x2120 kernel/signal.c:2852 arch_do_signal_or_restart+0x9c/0x730 arch/x86/kernel/signal.c:868 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x191/0x220 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:300 do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - In the Linux kernel, the following vulnerability has been resolved: KVM: VMX: Always clear vmx->fail on
    emulation_required Revert a relatively recent change that set vmx->fail if the vCPU is in L2 and
    emulation_required is true, as that behavior is completely bogus. Setting vmx->fail and synthesizing a VM-
    Exit is contradictory and wrong: (a) it's impossible to have both a VM-Fail and VM-Exit (b)
    vmcs.EXIT_REASON is not modified on VM-Fail (c) emulation_required refers to guest state and guest state
    checks are always VM-Exits, not VM-Fails. For KVM specifically, emulation_required is handled before
    nested exits in __vmx_handle_exit(), thus setting vmx->fail has no immediate effect, i.e. KVM calls into
    handle_invalid_guest_state() and vmx->fail is ignored. Setting vmx->fail can ultimately result in a WARN
    in nested_vmx_vmexit() firing when tearing down the VM as KVM never expects vmx->fail to be set when L2 is
    active, KVM always reflects those errors into L1. ------------[ cut here ]------------ WARNING: CPU: 0
    PID: 21158 at arch/x86/kvm/vmx/nested.c:4548 nested_vmx_vmexit+0x16bd/0x17e0
    arch/x86/kvm/vmx/nested.c:4547 Modules linked in: CPU: 0 PID: 21158 Comm: syz-executor.1 Not tainted
    5.16.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google
    01/01/2011 RIP: 0010:nested_vmx_vmexit+0x16bd/0x17e0 arch/x86/kvm/vmx/nested.c:4547 Code: <0f> 0b e9 2e f8
    ff ff e8 57 b3 5d 00 0f 0b e9 00 f1 ff ff 89 e9 80 Call Trace: vmx_leave_nested
    arch/x86/kvm/vmx/nested.c:6220 [inline] nested_vmx_free_vcpu+0x83/0xc0 arch/x86/kvm/vmx/nested.c:330
    vmx_free_vcpu+0x11f/0x2a0 arch/x86/kvm/vmx/vmx.c:6799 kvm_arch_vcpu_destroy+0x6b/0x240
    arch/x86/kvm/x86.c:10989 kvm_vcpu_destroy+0x29/0x90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:441
    kvm_free_vcpus arch/x86/kvm/x86.c:11426 [inline] kvm_arch_destroy_vm+0x3ef/0x6b0 arch/x86/kvm/x86.c:11545
    kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1189 [inline] kvm_put_kvm+0x751/0xe40
    arch/x86/kvm/../../../virt/kvm/kvm_main.c:1220 kvm_vcpu_release+0x53/0x60
    arch/x86/kvm/../../../virt/kvm/kvm_main.c:3489 __fput+0x3fc/0x870 fs/file_table.c:280
    task_work_run+0x146/0x1c0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:32 [inline]
    do_exit+0x705/0x24f0 kernel/exit.c:832 do_group_exit+0x168/0x2d0 kernel/exit.c:929
    get_signal+0x1740/0x2120 kernel/signal.c:2852 arch_do_signal_or_restart+0x9c/0x730
    arch/x86/kernel/signal.c:868 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop
    kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x191/0x220 kernel/entry/common.c:207
    __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x2e/0x70
    kernel/entry/common.c:300 do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86
    entry_SYSCALL_64_after_hwframe+0x44/0xae (CVE-2021-47092)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - In the Linux kernel, the following vulnerability has been resolved: KVM: VMX: Always clear vmx->fail on     emulation_required Revert a relatively recent change that set vmx->fail if the vCPU is in L2 and     emulation_required is true, as that behavior is completely bogus. Setting vmx->fail and synthesizing a VM-     Exit is contradictory and wrong: (a) it's impossible to have both a VM-Fail and VM-Exit (b)     vmcs.EXIT_REASON is not modified on VM-Fail (c) emulation_required refers to guest state and guest state     checks are always VM-Exits, not VM-Fails. For KVM specifically, emulation_required is handled before     nested exits in __vmx_handle_exit(), thus setting vmx->fail has no immediate effect, i.e. KVM calls into     handle_invalid_guest_state() and vmx->fail is ignored. Setting vmx->fail can ultimately result in a WARN     in nested_vmx_vmexit() firing when tearing down the VM as KVM never expects vmx->fail to be set when L2 is     active, KVM always reflects those errors into L1. ------------[ cut here ]------------ WARNING: CPU: 0     PID: 21158 at arch/x86/kvm/vmx/nested.c:4548 nested_vmx_vmexit+0x16bd/0x17e0     arch/x86/kvm/vmx/nested.c:4547 Modules linked in: CPU: 0 PID: 21158 Comm: syz-executor.1 Not tainted     5.16.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google     01/01/2011 RIP: 0010:nested_vmx_vmexit+0x16bd/0x17e0 arch/x86/kvm/vmx/nested.c:4547 Code: <0f> 0b e9 2e f8     ff ff e8 57 b3 5d 00 0f 0b e9 00 f1 ff ff 89 e9 80 Call Trace: vmx_leave_nested     arch/x86/kvm/vmx/nested.c:6220 [inline] nested_vmx_free_vcpu+0x83/0xc0 arch/x86/kvm/vmx/nested.c:330     vmx_free_vcpu+0x11f/0x2a0 arch/x86/kvm/vmx/vmx.c:6799 kvm_arch_vcpu_destroy+0x6b/0x240     arch/x86/kvm/x86.c:10989 kvm_vcpu_destroy+0x29/0x90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:441     kvm_free_vcpus arch/x86/kvm/x86.c:11426 [inline] kvm_arch_destroy_vm+0x3ef/0x6b0 arch/x86/kvm/x86.c:11545     kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1189 [inline] kvm_put_kvm+0x751/0xe40     arch/x86/kvm/../../../virt/kvm/kvm_main.c:1220 kvm_vcpu_release+0x53/0x60     arch/x86/kvm/../../../virt/kvm/kvm_main.c:3489 __fput+0x3fc/0x870 fs/file_table.c:280     task_work_run+0x146/0x1c0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:32 [inline]     do_exit+0x705/0x24f0 kernel/exit.c:832 do_group_exit+0x168/0x2d0 kernel/exit.c:929     get_signal+0x1740/0x2120 kernel/signal.c:2852 arch_do_signal_or_restart+0x9c/0x730     arch/x86/kernel/signal.c:868 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop     kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x191/0x220 kernel/entry/common.c:207
    __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x2e/0x70     kernel/entry/common.c:300 do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86     entry_SYSCALL_64_after_hwframe+0x44/0xae (CVE-2021-47092)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
454971	Google: sys-kernel/lakitu-kernel-5_15: security update to 17523.0.0	Tenable Cloud Security	Google COS Security Checks	Local	medium
454971	Google: sys-kernel/lakitu-kernel-5_15: security update to 17523.0.0	Tenable Self-Hosted Container Security	Google COS Security Checks	Local	medium
239060	TencentOS Server 4: kernel (TSSA-2024:0958)	Nessus	Tencent Local Security Checks	Local	high
224394	Linux Distros Unpatched Vulnerability : CVE-2021-47092	Nessus	Misc.	Local	medium

Detections

Analytics

CVE-2021-47092

medium

Tenable Plugins

medium

medium

high

medium