222 lines
13 KiB
JSON
222 lines
13 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-98464",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-09-25T10:25:14.350Z",
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"datePublished": "2026-10-18T15:15:16.624Z",
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"dateUpdated": "2026-10-24T14:08:56.354Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-24T14:08:56.354Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"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."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
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"baseScore": 9.3,
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"baseSeverity": "CRITICAL"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:L - Under KVM_RUN, a guest supervisor ECALL follows kvm_riscv_vcpu_exit()->kvm_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's 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."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"arch/riscv/kvm/vcpu_timer.c"
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],
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"versions": [
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{
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"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
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"lessThan": "9bdbae64ae0dab93041ebc57ec4e93def793fc2d",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
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"lessThan": "2af03b606aadaaeb386658ef798c79bdcdef87c1",
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"status": "affected",
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"lessThan": "e66aced74f0122380603c9910a71d77618b28f0e",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
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"lessThan": "ea91f05a55b807ead3166546a2c75f4185ca645f",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
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"lessThan": "3cc6184bd5920c9685d87f4e260568feba08650d",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "3a9f66cb25e18a3eeca36c08d9f823a35b3ddc22",
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"lessThan": "aaad136d56d91252517272b68cd533e5714698d5",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"arch/riscv/kvm/vcpu_timer.c"
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],
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"versions": [
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{
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"version": "5.16",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "5.16",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.1.189",
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"lessThanOrEqual": "6.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.158",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.112",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.55",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2.9",
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"lessThanOrEqual": "7.2.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.3",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.16",
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"versionEndExcluding": "6.1.189"
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/9bdbae64ae0dab93041ebc57ec4e93def793fc2d"
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},
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{
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"url": "https://git.kernel.org/stable/c/2af03b606aadaaeb386658ef798c79bdcdef87c1"
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},
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{
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"url": "https://git.kernel.org/stable/c/e66aced74f0122380603c9910a71d77618b28f0e"
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},
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{
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"url": "https://git.kernel.org/stable/c/ea91f05a55b807ead3166546a2c75f4185ca645f"
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},
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{
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"url": "https://git.kernel.org/stable/c/3cc6184bd5920c9685d87f4e260568feba08650d"
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},
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{
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"url": "https://git.kernel.org/stable/c/aaad136d56d91252517272b68cd533e5714698d5"
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}
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],
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"title": "RISC-V: KVM: Synchronize hrtimer callback during teardown",
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"x_generator": {
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"engine": "bippy-1.2.0"
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}
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}
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}
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} |