{"api_version":"1","generated_at":"2026-08-06T09:09:28+00:00","cve":"CVE-2024-40953","urls":{"html":"https://cve.report/CVE-2024-40953","api":"https://cve.report/api/cve/CVE-2024-40953.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2024-40953","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2024-40953"},"summary":{"title":"KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin()","description":"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->last_boosted_vcpu to ensure the\nloads and stores are atomic.  In the extremely unlikely scenario the\ncompiler tears the stores, it's 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->vcpu_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 -> 0x00000000","state":"PUBLISHED","assigner":"Linux","published_at":"2024-07-12 13:15:17","updated_at":"2026-08-04 11:19:08"},"problem_types":["CWE-362"],"metrics":[{"version":"3.1","source":"nvd@nist.gov","type":"Primary","score":"4.7","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":4.7,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}},{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.9","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H","baseScore":7.9,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.9","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H","data":{"baseScore":7.9,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/92c77807d938145c7c3350c944ef9f39d7f6017c","name":"https://git.kernel.org/stable/c/92c77807d938145c7c3350c944ef9f39d7f6017c","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4c141136a28421b78f34969b25a4fa32e06e2180","name":"https://git.kernel.org/stable/c/4c141136a28421b78f34969b25a4fa32e06e2180","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html","name":"https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/95c8dd79f3a14df96b3820b35b8399bd91b2be60","name":"https://git.kernel.org/stable/c/95c8dd79f3a14df96b3820b35b8399bd91b2be60","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a937ef951bba72f48d2402451419d725d70dba20","name":"https://git.kernel.org/stable/c/a937ef951bba72f48d2402451419d725d70dba20","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/82bd728a06e55f5b5f93d10ce67f4fe7e689853a","name":"https://git.kernel.org/stable/c/82bd728a06e55f5b5f93d10ce67f4fe7e689853a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/71fbc3af3dacb26c3aa2f30bb3ab05c44d082c84","name":"https://git.kernel.org/stable/c/71fbc3af3dacb26c3aa2f30bb3ab05c44d082c84","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/49f683b41f28918df3e51ddc0d928cb2e934ccdb","name":"https://git.kernel.org/stable/c/49f683b41f28918df3e51ddc0d928cb2e934ccdb","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/11a772d5376aa6d3e2e69b5b5c585f79b60c0e17","name":"https://git.kernel.org/stable/c/11a772d5376aa6d3e2e69b5b5c585f79b60c0e17","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html","name":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2024-40953","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2024-40953","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42 11a772d5376aa6d3e2e69b5b5c585f79b60c0e17 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42 4c141136a28421b78f34969b25a4fa32e06e2180 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42 71fbc3af3dacb26c3aa2f30bb3ab05c44d082c84 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42 82bd728a06e55f5b5f93d10ce67f4fe7e689853a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42 92c77807d938145c7c3350c944ef9f39d7f6017c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42 a937ef951bba72f48d2402451419d725d70dba20 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42 95c8dd79f3a14df96b3820b35b8399bd91b2be60 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 217ece6129f2d3b4fdd18d9e79be9e43d8d14a42 49f683b41f28918df3e51ddc0d928cb2e934ccdb git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.39","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.39 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.19.323 4.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.4.285 5.4.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.228 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.169 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.96 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.36 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.9.7 6.9.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.10 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2024","cve_id":"40953","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"linux","cpe5":"linux_kernel","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"providerMetadata":{"dateUpdated":"2025-11-03T21:58:17.097Z","orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE"},"references":[{"tags":["x_transferred"],"url":"https://git.kernel.org/stable/c/92c77807d938145c7c3350c944ef9f39d7f6017c"},{"tags":["x_transferred"],"url":"https://git.kernel.org/stable/c/a937ef951bba72f48d2402451419d725d70dba20"},{"tags":["x_transferred"],"url":"https://git.kernel.org/stable/c/95c8dd79f3a14df96b3820b35b8399bd91b2be60"},{"tags":["x_transferred"],"url":"https://git.kernel.org/stable/c/49f683b41f28918df3e51ddc0d928cb2e934ccdb"},{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html"},{"url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"}],"title":"CVE Program Container"},{"metrics":[{"other":{"content":{"id":"CVE-2024-40953","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2024-09-10T17:03:52.034893Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2024-09-11T17:34:24.499Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["virt/kvm/kvm_main.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"11a772d5376aa6d3e2e69b5b5c585f79b60c0e17","status":"affected","version":"217ece6129f2d3b4fdd18d9e79be9e43d8d14a42","versionType":"git"},{"lessThan":"4c141136a28421b78f34969b25a4fa32e06e2180","status":"affected","version":"217ece6129f2d3b4fdd18d9e79be9e43d8d14a42","versionType":"git"},{"lessThan":"71fbc3af3dacb26c3aa2f30bb3ab05c44d082c84","status":"affected","version":"217ece6129f2d3b4fdd18d9e79be9e43d8d14a42","versionType":"git"},{"lessThan":"82bd728a06e55f5b5f93d10ce67f4fe7e689853a","status":"affected","version":"217ece6129f2d3b4fdd18d9e79be9e43d8d14a42","versionType":"git"},{"lessThan":"92c77807d938145c7c3350c944ef9f39d7f6017c","status":"affected","version":"217ece6129f2d3b4fdd18d9e79be9e43d8d14a42","versionType":"git"},{"lessThan":"a937ef951bba72f48d2402451419d725d70dba20","status":"affected","version":"217ece6129f2d3b4fdd18d9e79be9e43d8d14a42","versionType":"git"},{"lessThan":"95c8dd79f3a14df96b3820b35b8399bd91b2be60","status":"affected","version":"217ece6129f2d3b4fdd18d9e79be9e43d8d14a42","versionType":"git"},{"lessThan":"49f683b41f28918df3e51ddc0d928cb2e934ccdb","status":"affected","version":"217ece6129f2d3b4fdd18d9e79be9e43d8d14a42","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["virt/kvm/kvm_main.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.39"},{"lessThan":"2.6.39","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"4.19.*","status":"unaffected","version":"4.19.323","versionType":"semver"},{"lessThanOrEqual":"5.4.*","status":"unaffected","version":"5.4.285","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.228","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.169","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.96","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.36","versionType":"semver"},{"lessThanOrEqual":"6.9.*","status":"unaffected","version":"6.9.7","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"6.10","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"4.19.323","versionStartIncluding":"2.6.39","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.4.285","versionStartIncluding":"2.6.39","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.228","versionStartIncluding":"2.6.39","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.169","versionStartIncluding":"2.6.39","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.96","versionStartIncluding":"2.6.39","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.36","versionStartIncluding":"2.6.39","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.9.7","versionStartIncluding":"2.6.39","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.10","versionStartIncluding":"2.6.39","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"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->last_boosted_vcpu to ensure the\nloads and stores are atomic.  In the extremely unlikely scenario the\ncompiler tears the stores, it's 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->vcpu_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 -> 0x00000000"}],"metrics":[{"cvssV3_1":{"baseScore":7.9,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-08-04T09:27:18.680Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/11a772d5376aa6d3e2e69b5b5c585f79b60c0e17"},{"url":"https://git.kernel.org/stable/c/4c141136a28421b78f34969b25a4fa32e06e2180"},{"url":"https://git.kernel.org/stable/c/71fbc3af3dacb26c3aa2f30bb3ab05c44d082c84"},{"url":"https://git.kernel.org/stable/c/82bd728a06e55f5b5f93d10ce67f4fe7e689853a"},{"url":"https://git.kernel.org/stable/c/92c77807d938145c7c3350c944ef9f39d7f6017c"},{"url":"https://git.kernel.org/stable/c/a937ef951bba72f48d2402451419d725d70dba20"},{"url":"https://git.kernel.org/stable/c/95c8dd79f3a14df96b3820b35b8399bd91b2be60"},{"url":"https://git.kernel.org/stable/c/49f683b41f28918df3e51ddc0d928cb2e934ccdb"}],"title":"KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2024-40953","datePublished":"2024-07-12T12:31:56.832Z","dateReserved":"2024-07-12T12:17:45.592Z","dateUpdated":"2026-08-04T09:27:18.680Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2024-07-12 13:15:17","lastModifiedDate":"2026-08-04 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Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin()","CVE":"CVE-2024-40953","Year":"2024"},"notes":[{"CveYear":"2024","CveId":"40953","Ordinal":"1","NoteData":"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->last_boosted_vcpu to ensure the\nloads and stores are atomic.  In the extremely unlikely scenario the\ncompiler tears the stores, it's 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->vcpu_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 -> 0x00000000","Type":"Description","Title":"KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin()"}]}}}