GHSA-J7WR-633C-VHMR
Vulnerability from github – Published: 2024-07-12 15:31 – Updated: 2025-11-04 00:30In 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": [],
"aliases": [
"CVE-2024-40953"
],
"database_specific": {
"cwe_ids": [
"CWE-362"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-07-12T13:15:17Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin()\n\nUse {READ,WRITE}_ONCE() to access kvm-\u003elast_boosted_vcpu to ensure the\nloads and stores are atomic. In the extremely unlikely scenario the\ncompiler tears the stores, it\u0027s theoretically possible for KVM to attempt\nto get a vCPU using an out-of-bounds index, e.g. if the write is split\ninto multiple 8-bit stores, and is paired with a 32-bit load on a VM with\n257 vCPUs:\n\n CPU0 CPU1\n last_boosted_vcpu = 0xff;\n\n (last_boosted_vcpu = 0x100)\n last_boosted_vcpu[15:8] = 0x01;\n i = (last_boosted_vcpu = 0x1ff)\n last_boosted_vcpu[7:0] = 0x00;\n\n vcpu = kvm-\u003evcpu_array[0x1ff];\n\nAs detected by KCSAN:\n\n BUG: KCSAN: data-race in kvm_vcpu_on_spin [kvm] / kvm_vcpu_on_spin [kvm]\n\n write to 0xffffc90025a92344 of 4 bytes by task 4340 on cpu 16:\n kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4112) kvm\n handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel\n vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:?\n\t\t arch/x86/kvm/vmx/vmx.c:6606) kvm_intel\n vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm\n kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm\n kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm\n __se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890)\n __x64_sys_ioctl (fs/ioctl.c:890)\n x64_sys_call (arch/x86/entry/syscall_64.c:33)\n do_syscall_64 (arch/x86/entry/common.c:?)\n entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n\n read to 0xffffc90025a92344 of 4 bytes by task 4342 on cpu 4:\n kvm_vcpu_on_spin (arch/x86/kvm/../../../virt/kvm/kvm_main.c:4069) kvm\n handle_pause (arch/x86/kvm/vmx/vmx.c:5929) kvm_intel\n vmx_handle_exit (arch/x86/kvm/vmx/vmx.c:?\n\t\t\tarch/x86/kvm/vmx/vmx.c:6606) kvm_intel\n vcpu_run (arch/x86/kvm/x86.c:11107 arch/x86/kvm/x86.c:11211) kvm\n kvm_arch_vcpu_ioctl_run (arch/x86/kvm/x86.c:?) kvm\n kvm_vcpu_ioctl (arch/x86/kvm/../../../virt/kvm/kvm_main.c:?) kvm\n __se_sys_ioctl (fs/ioctl.c:52 fs/ioctl.c:904 fs/ioctl.c:890)\n __x64_sys_ioctl (fs/ioctl.c:890)\n x64_sys_call (arch/x86/entry/syscall_64.c:33)\n do_syscall_64 (arch/x86/entry/common.c:?)\n entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n\n value changed: 0x00000012 -\u003e 0x00000000",
"id": "GHSA-j7wr-633c-vhmr",
"modified": "2025-11-04T00:30:55Z",
"published": "2024-07-12T15:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-40953"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/11a772d5376aa6d3e2e69b5b5c585f79b60c0e17"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/49f683b41f28918df3e51ddc0d928cb2e934ccdb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4c141136a28421b78f34969b25a4fa32e06e2180"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/71fbc3af3dacb26c3aa2f30bb3ab05c44d082c84"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/82bd728a06e55f5b5f93d10ce67f4fe7e689853a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/92c77807d938145c7c3350c944ef9f39d7f6017c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/95c8dd79f3a14df96b3820b35b8399bd91b2be60"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a937ef951bba72f48d2402451419d725d70dba20"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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