CVE-2026-98464
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.
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On upstream master 62cc90241548, generic KASAN reported:
The object was allocated by KVM_CREATE_VCPU and freed concurrently by:
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.
Technical details traces, logs and code from the original report
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 kvm_destroy_vcpus kvm_arch_destroy_vm kvm_destroy_vm __fput
CVSS
NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 0.17 %
- Percentile among all scored CVEs
- 6
- Score date
- 10/21/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
References
Show 6 references
- https://git.kernel.org/stable/c/2af03b606aadaaeb386658ef798c79bdcdef87c1
- https://git.kernel.org/stable/c/3cc6184bd5920c9685d87f4e260568feba08650d
- https://git.kernel.org/stable/c/9bdbae64ae0dab93041ebc57ec4e93def793fc2d
- https://git.kernel.org/stable/c/aaad136d56d91252517272b68cd533e5714698d5
- https://git.kernel.org/stable/c/e66aced74f0122380603c9910a71d77618b28f0e
- https://git.kernel.org/stable/c/ea91f05a55b807ead3166546a2c75f4185ca645f
Raw JSON (NVD)
Show
{
"id": "CVE-2026-98464",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
"lessThan": "9bdbae64ae0dab93041ebc57ec4e93def793fc2d",
"versionType": "git"
},
{
"status": "affected",
"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
"lessThan": "2af03b606aadaaeb386658ef798c79bdcdef87c1",
"versionType": "git"
},
{
"status": "affected",
"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
"lessThan": "e66aced74f0122380603c9910a71d77618b28f0e",
"versionType": "git"
},
{
"status": "affected",
"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
"lessThan": "ea91f05a55b807ead3166546a2c75f4185ca645f",
"versionType": "git"
},
{
"status": "affected",
"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
"lessThan": "3cc6184bd5920c9685d87f4e260568feba08650d",
"versionType": "git"
},
{
"status": "affected",
"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
"lessThan": "aaad136d56d91252517272b68cd533e5714698d5",
"versionType": "git"
}
],
"programFiles": [
"arch/riscv/kvm/vcpu_timer.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.16"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.16",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.189",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.112",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.55",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.9",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"arch/riscv/kvm/vcpu_timer.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-18T16:16:56.873",
"references": [
{
"url": "https://git.kernel.org/stable/c/2af03b606aadaaeb386658ef798c79bdcdef87c1",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/3cc6184bd5920c9685d87f4e260568feba08650d",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9bdbae64ae0dab93041ebc57ec4e93def793fc2d",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/aaad136d56d91252517272b68cd533e5714698d5",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e66aced74f0122380603c9910a71d77618b28f0e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/ea91f05a55b807ead3166546a2c75f4185ca645f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"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."
}
],
"lastModified": "2026-10-19T10:18:56.097",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}