CVE-2026-98464 (GCVE-0-2026-98464)
Vulnerability from cvelistv5
Published
2026-10-18 15:15
Modified
2026-10-24 14:08
Severity ?
9.3 (Critical) - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: RISC-V: KVM: Synchronize hrtimer callback during teardown The non-Sstc hrtimer callback clears next_set before its final uses of the enclosing vCPU. If teardown observes next_set as false while the callback is still running, kvm_riscv_vcpu_timer_cancel() skips hrtimer_cancel() and kvm_destroy_vcpus() can free the vCPU before the callback enters kvm_riscv_vcpu_set_interrupt(). A guest can arm the timer with SBI TIME and request shutdown with SBI legacy shutdown or SRST. A VMM that honors KVM_EXIT_SYSTEM_EVENT and destroys the VM supplies the teardown side of the race; no post-launch host ioctl is needed to arm or request teardown. On upstream master 62cc90241548, generic KASAN reported: BUG: KASAN: slab-use-after-free in do_raw_spin_lock Write of size 4 at addr ff60000005e58898 kvm_riscv_vcpu_set_interrupt kvm_riscv_vcpu_hrtimer_expired __hrtimer_run_queues hrtimer_interrupt The object was allocated by KVM_CREATE_VCPU and freed concurrently by: kvm_destroy_vcpus kvm_arch_destroy_vm kvm_destroy_vm __fput For deterministic validation, I added mdelay(1000) immediately after the existing next_set = false assignment. This only widens the existing post-clear callback window. A no-delay trace build naturally reached the callback-after-teardown-start/before-deinit ordering in 12 of 200 runs, but 1,500 stock-kernel stress iterations did not produce a KASAN report, so natural reproduction is timing-sensitive. Always invoke hrtimer_cancel() for an initialized timer. Preserve the existing -EINVAL result when the timer is no longer set, but only after synchronizing with a running callback. With this patch, hrtimer_cancel() blocked for the full widened callback window before vCPU destruction. KASAN reported no error in 100 fixed-and-widened runs or 200 fix-only timing-sweep runs.
References
Impacted products
Vendor Product Version
Linux Linux Version: 3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22
Version: 3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22
Version: 3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22
Version: 3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22
Version: 3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22
Version: 3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/riscv/kvm/vcpu_timer.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9bdbae64ae0dab93041ebc57ec4e93def793fc2d",
              "status": "affected",
              "version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
              "versionType": "git"
            },
            {
              "lessThan": "2af03b606aadaaeb386658ef798c79bdcdef87c1",
              "status": "affected",
              "version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
              "versionType": "git"
            },
            {
              "lessThan": "e66aced74f0122380603c9910a71d77618b28f0e",
              "status": "affected",
              "version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
              "versionType": "git"
            },
            {
              "lessThan": "ea91f05a55b807ead3166546a2c75f4185ca645f",
              "status": "affected",
              "version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
              "versionType": "git"
            },
            {
              "lessThan": "3cc6184bd5920c9685d87f4e260568feba08650d",
              "status": "affected",
              "version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
              "versionType": "git"
            },
            {
              "lessThan": "aaad136d56d91252517272b68cd533e5714698d5",
              "status": "affected",
              "version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/riscv/kvm/vcpu_timer.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.16"
            },
            {
              "lessThan": "5.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.189",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.158",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.112",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.55",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.9",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRISC-V: KVM: Synchronize hrtimer callback during teardown\n\nThe non-Sstc hrtimer callback clears next_set before its final uses of\nthe enclosing vCPU.  If teardown observes next_set as false while the\ncallback is still running, kvm_riscv_vcpu_timer_cancel() skips\nhrtimer_cancel() and kvm_destroy_vcpus() can free the vCPU before the\ncallback enters kvm_riscv_vcpu_set_interrupt().\n\nA guest can arm the timer with SBI TIME and request shutdown with SBI\nlegacy shutdown or SRST.  A VMM that honors KVM_EXIT_SYSTEM_EVENT and\ndestroys the VM supplies the teardown side of the race; no post-launch\nhost ioctl is needed to arm or request teardown.\n\nOn upstream master 62cc90241548, generic KASAN reported:\n\n  BUG: KASAN: slab-use-after-free in do_raw_spin_lock\n  Write of size 4 at addr ff60000005e58898\n\n  kvm_riscv_vcpu_set_interrupt\n  kvm_riscv_vcpu_hrtimer_expired\n  __hrtimer_run_queues\n  hrtimer_interrupt\n\nThe object was allocated by KVM_CREATE_VCPU and freed concurrently by:\n\n  kvm_destroy_vcpus\n  kvm_arch_destroy_vm\n  kvm_destroy_vm\n  __fput\n\nFor deterministic validation, I added mdelay(1000) immediately after\nthe existing next_set = false assignment.  This only widens the\nexisting post-clear callback window.  A no-delay trace build naturally\nreached the callback-after-teardown-start/before-deinit ordering in 12\nof 200 runs, but 1,500 stock-kernel stress iterations did not produce a\nKASAN report, so natural reproduction is timing-sensitive.\n\nAlways invoke hrtimer_cancel() for an initialized timer.  Preserve the\nexisting -EINVAL result when the timer is no longer set, but only after\nsynchronizing with a running callback.\n\nWith this patch, hrtimer_cancel() blocked for the full widened callback\nwindow before vCPU destruction.  KASAN reported no error in 100\nfixed-and-widened runs or 200 fix-only timing-sweep runs."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.3,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Under KVM_RUN, a guest supervisor ECALL follows kvm_riscv_vcpu_exit()-\u003ekvm_riscv_vcpu_sbi_ecall(); SBI TIME arms kvm_riscv_vcpu_update_hrtimer(), while shutdown/SRST drives teardown to the patched kvm_riscv_vcpu_timer_cancel(). This is local guest/hypervisor input, not a network protocol.\nAC:L - On a non-Sstc host, the guest chooses the timer deadline through SBI TIME and immediately issues shutdown/SRST, causing VMM teardown while the callback runs. The attacker creates both sides of the race, so the short scheduling window does not impose an attacker-uncontrollable condition.\nPR:N - kvm_riscv_vcpu_sbi_ecall() dispatches TIME and SRST or legacy shutdown from an already-running guest without any host credential or capability check; guest S-mode is within the untrusted VM authority, so no privilege in host KVM is required.\nUI:N - kvm_riscv_vcpu_sbi_system_reset() sets KVM_EXIT_SYSTEM_EVENT, after which a VMM that honors the guest\u0027s request tears down the VM automatically; no person must perform an additional action.\nS:C - The guest-triggered kvm_riscv_vcpu_hrtimer_expired() callback accesses host kernel memory after the host struct kvm_vcpu is freed, crossing the KVM guest-to-host isolation boundary.\nC:H - kvm_riscv_vcpu_hrtimer_expired() reconstructs and uses a freed vCPU, and kvm_riscv_vcpu_set_interrupt()/kvm_vcpu_kick() read reclaimed lock, wait, mode, and CPU state. Reuse of this UAF object can provide host-kernel memory disclosure primitives.\nI:H - kvm_riscv_vcpu_set_interrupt() acquires a raw spinlock and performs two __set_bit() writes through the freed vCPU before kicking it; if the slab object is reclaimed, these operations corrupt the new host object and provide exploitable UAF write primitives.\nA:H - KASAN recorded a four-byte slab-use-after-free write in do_raw_spin_lock after kvm_destroy_vcpus() freed the vCPU. Corrupting or following the reclaimed lock and wakeup state can oops, panic, or hang the host and its VMs."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:08:56.354Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9bdbae64ae0dab93041ebc57ec4e93def793fc2d"
        },
        {
          "url": "https://git.kernel.org/stable/c/2af03b606aadaaeb386658ef798c79bdcdef87c1"
        },
        {
          "url": "https://git.kernel.org/stable/c/e66aced74f0122380603c9910a71d77618b28f0e"
        },
        {
          "url": "https://git.kernel.org/stable/c/ea91f05a55b807ead3166546a2c75f4185ca645f"
        },
        {
          "url": "https://git.kernel.org/stable/c/3cc6184bd5920c9685d87f4e260568feba08650d"
        },
        {
          "url": "https://git.kernel.org/stable/c/aaad136d56d91252517272b68cd533e5714698d5"
        }
      ],
      "title": "RISC-V: KVM: Synchronize hrtimer callback during teardown",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98464",
    "datePublished": "2026-10-18T15:15:16.624Z",
    "dateReserved": "2026-09-25T10:25:14.350Z",
    "dateUpdated": "2026-10-24T14:08:56.354Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.