{"cve":"CVE-2024-53195","nvd":{"published":"2024-12-27T14:15:27.137","modified":"2026-10-30T13:17:45.370","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Get rid of userspace_irqchip_in_use\n\nImproper use of userspace_irqchip_in_use led to syzbot hitting the\nfollowing WARN_ON() in kvm_timer_update_irq():\n\nWARNING: CPU: 0 PID: 3281 at arch/arm64/kvm/arch_timer.c:459\nkvm_timer_update_irq+0x21c/0x394\nCall trace:\n  kvm_timer_update_irq+0x21c/0x394 arch/arm64/kvm/arch_timer.c:459\n  kvm_timer_vcpu_reset+0x158/0x684 arch/arm64/kvm/arch_timer.c:968\n  kvm_reset_vcpu+0x3b4/0x560 arch/arm64/kvm/reset.c:264\n  kvm_vcpu_set_target arch/arm64/kvm/arm.c:1553 [inline]\n  kvm_arch_vcpu_ioctl_vcpu_init arch/arm64/kvm/arm.c:1573 [inline]\n  kvm_arch_vcpu_ioctl+0x112c/0x1b3c arch/arm64/kvm/arm.c:1695\n  kvm_vcpu_ioctl+0x4ec/0xf74 virt/kvm/kvm_main.c:4658\n  vfs_ioctl fs/ioctl.c:51 [inline]\n  __do_sys_ioctl fs/ioctl.c:907 [inline]\n  __se_sys_ioctl fs/ioctl.c:893 [inline]\n  __arm64_sys_ioctl+0x108/0x184 fs/ioctl.c:893\n  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]\n  invoke_syscall+0x78/0x1b8 arch/arm64/kernel/syscall.c:49\n  el0_svc_common+0xe8/0x1b0 arch/arm64/kernel/syscall.c:132\n  do_el0_svc+0x40/0x50 arch/arm64/kernel/syscall.c:151\n  el0_svc+0x54/0x14c arch/arm64/kernel/entry-common.c:712\n  el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730\n  el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598\n\nThe following sequence led to the scenario:\n - Userspace creates a VM and a vCPU.\n - The vCPU is initialized with KVM_ARM_VCPU_PMU_V3 during\n   KVM_ARM_VCPU_INIT.\n - Without any other setup, such as vGIC or vPMU, userspace issues\n   KVM_RUN on the vCPU. Since the vPMU is requested, but not setup,\n   kvm_arm_pmu_v3_enable() fails in kvm_arch_vcpu_run_pid_change().\n   As a result, KVM_RUN returns after enabling the timer, but before\n   incrementing 'userspace_irqchip_in_use':\n   kvm_arch_vcpu_run_pid_change()\n       ret = kvm_arm_pmu_v3_enable()\n           if (!vcpu->arch.pmu.created)\n               return -EINVAL;\n       if (ret)\n           return ret;\n       [...]\n       if (!irqchip_in_kernel(kvm))\n           static_branch_inc(&userspace_irqchip_in_use);\n - Userspace ignores the error and issues KVM_ARM_VCPU_INIT again.\n   Since the timer is already enabled, control moves through the\n   following flow, ultimately hitting the WARN_ON():\n   kvm_timer_vcpu_reset()\n       if (timer->enabled)\n          kvm_timer_update_irq()\n              if (!userspace_irqchip())\n                  ret = kvm_vgic_inject_irq()\n                      ret = vgic_lazy_init()\n                          if (unlikely(!vgic_initialized(kvm)))\n                              if (kvm->arch.vgic.vgic_model !=\n                                  KVM_DEV_TYPE_ARM_VGIC_V2)\n                                      return -EBUSY;\n                  WARN_ON(ret);\n\nTheoretically, since userspace_irqchip_in_use's functionality can be\nsimply replaced by '!irqchip_in_kernel()', get rid of the static key\nto avoid the mismanagement, which also helps with the syzbot issue.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/38d7aacca09230fdb98a34194fec2af597e8e20d","https://git.kernel.org/stable/c/982a1461ab9cf3146302fe5a139ecb1f9b2d33fc","https://git.kernel.org/stable/c/c16e2dba39ff6ae84bb8dc9c8e0fb21d9b2f6f5c","https://git.kernel.org/stable/c/dd2f9861f27571d47998d71e7516bf7216db0b52","https://git.kernel.org/stable/c/fe425d5239a28c21e0c83ee7a8f4cb210d29fdb4"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-30T13:47:47.119061695+00:00"},"epss":{"cve":"CVE-2024-53195","score":0.0022,"percentile":0.1256,"date":"2026-10-30"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}