CVE-2024-53195
Vulnerability Scoring
Status: Received on 27 Dec 2024, 14:15 UTC
Published on: 27 Dec 2024, 14:15 UTC
CVSS Release:
CVE-2024-53195: In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Get rid of userspace_irqchip_in_use Improper use of userspace_irqchip_in_use led to syzbot hitting the following WARN_ON() in kvm_timer_update_irq(): WARNING: CPU: 0 PID: 3281 at arch/arm64/kvm/arch_timer.c:459 kvm_timer_update_irq+0x21c/0x394 Call trace: kvm_timer_update_irq+0x21c/0x394 arch/arm64/kvm/arch_timer.c:459 kvm_timer_vcpu_reset+0x158/0x684 arch/arm64/kvm/arch_timer.c:968 kvm_reset_vcpu+0x3b4/0x560 arch/arm64/kvm/reset.c:264 kvm_vcpu_set_target arch/arm64/kvm/arm.c:1553 [inline] kvm_arch_vcpu_ioctl_vcpu_init arch/arm64/kvm/arm.c:1573 [inline] kvm_arch_vcpu_ioctl+0x112c/0x1b3c arch/arm64/kvm/arm.c:1695 kvm_vcpu_ioctl+0x4ec/0xf74 virt/kvm/kvm_main.c:4658 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __arm64_sys_ioctl+0x108/0x184 fs/ioctl.c:893 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x78/0x1b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x1b0 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x40/0x50 arch/arm64/kernel/syscall.c:151 el0_svc+0x54/0x14c arch/arm64/kernel/entry-common.c:712 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598 The following sequence led to the scenario: - Userspace creates a VM and a vCPU. - The vCPU is initialized with KVM_ARM_VCPU_PMU_V3 during KVM_ARM_VCPU_INIT. - Without any other setup, such as vGIC or vPMU, userspace issues KVM_RUN on the vCPU. Since the vPMU is requested, but not setup, kvm_arm_pmu_v3_enable() fails in kvm_arch_vcpu_run_pid_change(). As a result, KVM_RUN returns after enabling the timer, but before incrementing 'userspace_irqchip_in_use': kvm_arch_vcpu_run_pid_change() ret = kvm_arm_pmu_v3_enable() if (!vcpu->arch.pmu.created) return -EINVAL; if (ret) return ret; [...] if (!irqchip_in_kernel(kvm)) static_branch_inc(&userspace_irqchip_in_use); - Userspace ignores the error and issues KVM_ARM_VCPU_INIT again. Since the timer is already enabled, control moves through the following flow, ultimately hitting the WARN_ON(): kvm_timer_vcpu_reset() if (timer->enabled) kvm_timer_update_irq() if (!userspace_irqchip()) ret = kvm_vgic_inject_irq() ret = vgic_lazy_init() if (unlikely(!vgic_initialized(kvm))) if (kvm->arch.vgic.vgic_model != KVM_DEV_TYPE_ARM_VGIC_V2) return -EBUSY; WARN_ON(ret); Theoretically, since userspace_irqchip_in_use's functionality can be simply replaced by '!irqchip_in_kernel()', get rid of the static key to avoid the mismanagement, which also helps with the syzbot issue.
The exploitability of CVE-2024-53195 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
No exploitability data is available for CVE-2024-53195.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2024-53195, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2024-53195, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
The EPSS score estimates the probability that this vulnerability will be exploited in the near future.
EPSS Score: 0.045% (probability of exploit)
EPSS Percentile: 18.4%
(lower percentile = lower relative risk)
This vulnerability is less risky than approximately 81.6% of others.
Unknown
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