CVE-2024-40953

Advisory lineage Upstream: 0 Downstream: 48
Modified
Published: 12 Jul 2024, 12:31
Last modified:11 May 2026, 20:23

Vulnerability Summary

Overall Risk (default)
low
19/100
CVSS Score
4.7 MEDIUM
v3.1 (nvd)
EPSS Score
0.01% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

12 Jul 2024, 12:31
Published
Vulnerability first disclosed
11 May 2026, 20:23
Last Modified
Vulnerability information updated

Description

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

CVSS Metrics

  • v3.1•MEDIUM•Score: 4.7CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.01%• Percentile: 2%

Techniques & Countermeasures

  • CWE-362•Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

    The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

Affected Systems

  • linux•linux

    ≥ 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42, < 11a772d5376aa6d3e2e69b5b5c585f79b60c0e17 | ≥ 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42, < 4c141136a28421b78f34969b25a4fa32e06e2180 | ≥ 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42, < 71fbc3af3dacb26c3aa2f30bb3ab05c44d082c84 | ≥ 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42, < 82bd728a06e55f5b5f93d10ce67f4fe7e689853a | ≥ 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42, < 92c77807d938145c7c3350c944ef9f39d7f6017c | ≥ 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42, < a937ef951bba72f48d2402451419d725d70dba20 | ≥ 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42, < 95c8dd79f3a14df96b3820b35b8399bd91b2be60 | ≥ 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42, < 49f683b41f28918df3e51ddc0d928cb2e934ccdb | 2.6.39

  • linux•linux_kernel

    ≥ 2.6.39, < 4.19.323 | ≥ 4.20, < 5.4.285 | ≥ 5.5, < 5.10.228 | ≥ 5.11, < 5.15.169 | ≥ 5.16, < 6.1.96 | ≥ 6.2, < 6.6.36 | ≥ 6.7, < 6.9.7 | 6.10:rc1 | 6.10:rc2 | 6.10:rc3 | 6.10:rc4

References (10)