CVE-2024-40953

2024-07-1213:15:17

Linux

web.nvd.nist.gov

linux kernel

cve-2024-40953

data race

AI Score

6.5

Confidence

Low

EPSS

Percentile

15.9%

JSON

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

Affected configurations

Vulners

Node

linuxlinux_kernelRange2.6.39–6.1.96

linuxlinux_kernelRange6.2.0–6.6.36

linuxlinux_kernelRange6.7.0–6.9.7

linuxlinux_kernelRange6.10.0≥

VendorProductVersionCPE
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

Vendor	Product	Version	CPE
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "virt/kvm/kvm_main.c"
    ],
    "versions": [
      {
        "version": "217ece6129f2",
        "lessThan": "92c77807d938",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "217ece6129f2",
        "lessThan": "a937ef951bba",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "217ece6129f2",
        "lessThan": "95c8dd79f3a1",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "217ece6129f2",
        "lessThan": "49f683b41f28",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "virt/kvm/kvm_main.c"
    ],
    "versions": [
      {
        "version": "2.6.39",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "2.6.39",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.96",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.36",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9.7",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]