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

KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin()

Use {READ,WRITE}_ONCE() to access kvm->last_boosted_vcpu to ensure the
loads and stores are atomic. In the extremely unlikely scenario the
compiler tears the stores, it's theoretically possible for KVM to attempt
to get a vCPU using an out-of-bounds index, e.g. if the write is split
into multiple 8-bit stores, and is paired with a 32-bit load on a VM with
257 vCPUs:

CPU0 CPU1
last_boosted_vcpu = 0xff;

(last_boosted_vcpu = 0x100)
last_boosted_vcpu[15:8] = 0x01;
i = (last_boosted_vcpu = 0x1ff)
last_boosted_vcpu[7:0] = 0x00;

vcpu = kvm->vcpu_array[0x1ff];

As detected by KCSAN:

BUG: KCSAN: data-race in kvm_vcpu_on_spin [kvm] / kvm_vcpu_on_spin [kvm]

write to 0xffffc90025a92344 of 4 bytes by task 4340 on cpu 16:
kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4112) kvm
handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel
vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:?
arch/x86/kvm/vmx/vmx.c:6606) kvm_intel
vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm
kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm
kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm
__se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890)
__x64_sys_ioctl (fs/ioctl.c:890)
x64_sys_call (arch/x86/entry/syscall_64.c:33)
do_syscall_64 (arch/x86/entry/common.c:?)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

read to 0xffffc90025a92344 of 4 bytes by task 4342 on cpu 4:
kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4069) kvm
handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel
vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:?
arch/x86/kvm/vmx/vmx.c:6606) kvm_intel
vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm
kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm
kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm
__se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890)
__x64_sys_ioctl (fs/ioctl.c:890)
x64_sys_call (arch/x86/entry/syscall_64.c:33)
do_syscall_64 (arch/x86/entry/common.c:?)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

value changed: 0x00000012 -> 0x00000000
Advisories
Source ID Title
Debian DLA Debian DLA DLA-4008-1 linux-6.1 security update
Debian DLA Debian DLA DLA-4075-1 linux security update
Debian DSA Debian DSA DSA-5731-1 linux security update
Ubuntu USN Ubuntu USN USN-6999-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-6999-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7004-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7005-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7005-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7008-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7029-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7288-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7288-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7289-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7289-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7289-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7289-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7291-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7293-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7294-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7294-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7294-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7294-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7295-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7305-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7308-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7331-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7388-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7389-1 Linux kernel (NVIDIA Tegra) vulnerabilities
Ubuntu USN Ubuntu USN USN-7390-1 Linux kernel (Xilinx ZynqMP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7393-1 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7401-1 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7413-1 Linux kernel (IoT) vulnerabilities
Ubuntu USN Ubuntu USN USN-7458-1 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7539-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7540-1 Linux kernel (Raspberry Pi) vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 03 Nov 2025 22:30:00 +0000

Type Values Removed Values Added
References

Mon, 03 Nov 2025 21:30:00 +0000

Type Values Removed Values Added
References

Wed, 17 Sep 2025 15:15:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc4:*:*:*:*:*:*

Fri, 08 Nov 2024 16:00:00 +0000


Tue, 22 Oct 2024 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 22 Oct 2024 14:30:00 +0000


Thu, 12 Sep 2024 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 11 Sep 2024 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-11-03T21:58:17.097Z

Reserved: 2024-07-12T12:17:45.592Z

Link: CVE-2024-40953

cve-icon Vulnrichment

Updated: 2025-11-03T21:58:17.097Z

cve-icon NVD

Status : Modified

Published: 2024-07-12T13:15:17.560

Modified: 2025-11-03T22:17:17.017

Link: CVE-2024-40953

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-07-12T00:00:00Z

Links: CVE-2024-40953 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-07-12T22:00:58Z