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UBUNTU-CVE-2024-53195 Moderate

UBUNTU-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.

Exploit probability Not scored
Published December 27, 2024
Required by Not available
Last source change August 19, 2026

02 / AFFECTED SOFTWARE

Affected packages

Ubuntu:22.04:LTS linux-nvidia

77 explicit affected versions

Ubuntu:22.04:LTS linux-nvidia-6.8

17 explicit affected versions

Ubuntu:18.04:LTS linux-aws-5.0

6 explicit affected versions

Ubuntu:Pro:Realtime:22.04:LTS linux-intel-iot-realtime

68 explicit affected versions

Ubuntu:24.04:LTS linux-nvidia-lowlatency

15 explicit affected versions

Ubuntu:22.04:LTS linux-gcp-6.8

16 explicit affected versions

Ubuntu:22.04:LTS linux-starfive-6.5

11 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-iot

53 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-azure

116 explicit affected versions

Ubuntu:22.04:LTS linux-ibm

89 explicit affected versions

Ubuntu:18.04:LTS linux-oem

50 explicit affected versions

Ubuntu:24.04:LTS linux-riscv

21 explicit affected versions

Ubuntu:20.04:LTS linux-aws-5.11

12 explicit affected versions

Ubuntu:22.04:LTS linux-oem-6.5

19 explicit affected versions

Ubuntu:20.04:LTS linux-raspi2

6 explicit affected versions

Ubuntu:22.04:LTS linux

100 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-azure-fde-5.15

61 explicit affected versions

Ubuntu:22.04:LTS linux-gkeop

85 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-lowlatency-hwe-5.15

84 explicit affected versions

Ubuntu:Pro:FIPS-updates:20.04:LTS linux-fips

91 explicit affected versions

Ubuntu:22.04:LTS linux-azure

86 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-kvm

121 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-gcp-5.15

76 explicit affected versions

Ubuntu:22.04:LTS linux-riscv-6.5

10 explicit affected versions

Ubuntu:22.04:LTS linux-ibm-6.8

12 explicit affected versions

Ubuntu:24.04:LTS linux-oem-6.8

19 explicit affected versions

Ubuntu:22.04:LTS linux-gke

90 explicit affected versions

Ubuntu:Pro:14.04:LTS linux

191 explicit affected versions

Ubuntu:22.04:LTS linux-azure-5.19

7 explicit affected versions

Ubuntu:22.04:LTS linux-raspi

84 explicit affected versions

Ubuntu:22.04:LTS linux-oracle-6.8

16 explicit affected versions

Ubuntu:22.04:LTS linux-gcp-6.5

13 explicit affected versions

Ubuntu:Pro:FIPS-updates:18.04:LTS linux-azure-fips

85 explicit affected versions

Ubuntu:24.04:LTS linux-nvidia

18 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.14

35 explicit affected versions

Ubuntu:Pro:FIPS-updates:22.04:LTS linux-gcp-fips

51 explicit affected versions

Ubuntu:22.04:LTS linux-nvidia-tegra

50 explicit affected versions

Ubuntu:20.04:LTS linux-gke-5.15

18 explicit affected versions

Ubuntu:Pro:FIPS-updates:22.04:LTS linux-azure-fips

42 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-oracle

118 explicit affected versions

Ubuntu:22.04:LTS linux-lowlatency-hwe-6.2

10 explicit affected versions

Ubuntu:22.04:LTS linux-azure-fde

64 explicit affected versions

Ubuntu:24.04:LTS linux-oracle

21 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-hwe-5.4

120 explicit affected versions

Ubuntu:20.04:LTS linux-aws-5.13

13 explicit affected versions

Ubuntu:20.04:LTS linux-aws-5.8

4 explicit affected versions

Ubuntu:16.04:LTS linux-hwe-edge

23 explicit affected versions

Ubuntu:24.04:LTS linux

26 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-gcp

124 explicit affected versions

Ubuntu:Pro:FIPS:18.04:LTS linux-gcp-fips

1 explicit affected versions

Ubuntu:24.04:LTS linux-raspi-realtime

1 explicit affected versions

Ubuntu:20.04:LTS linux-hwe-5.8

21 explicit affected versions

Ubuntu:20.04:LTS linux-hwe-5.13

16 explicit affected versions

Ubuntu:22.04:LTS linux-azure-6.8

13 explicit affected versions

Ubuntu:Pro:FIPS-updates:20.04:LTS linux-aws-fips

76 explicit affected versions

Ubuntu:24.04:LTS linux-aws

22 explicit affected versions

Ubuntu:18.04:LTS linux-oracle-5.0

7 explicit affected versions

Ubuntu:20.04:LTS linux-riscv

12 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-oracle

111 explicit affected versions

Ubuntu:24.04:LTS linux-azure-6.11

1 explicit affected versions

Ubuntu:20.04:LTS linux-gcp-5.11

12 explicit affected versions

Ubuntu:22.04:LTS linux-azure-6.5

14 explicit affected versions

Ubuntu:22.04:LTS linux-intel-iot-realtime

1 explicit affected versions

Ubuntu:22.04:LTS linux-lowlatency-hwe-6.8

14 explicit affected versions

Ubuntu:20.04:LTS linux-intel-5.13

7 explicit affected versions

Ubuntu:24.04:LTS linux-nvidia-tegra

2 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-azure-5.4

104 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.13

12 explicit affected versions

Ubuntu:22.04:LTS linux-azure-fde-6.2

10 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-raspi

105 explicit affected versions

Ubuntu:20.04:LTS linux-oracle-5.11

12 explicit affected versions

Ubuntu:Pro:Realtime:22.04:LTS linux-realtime-6.8

16 explicit affected versions

Ubuntu:Pro:14.04:LTS linux-aws

120 explicit affected versions

Ubuntu:22.04:LTS linux-nvidia-tegra-igx

45 explicit affected versions

Ubuntu:24.04:LTS linux-gkeop

8 explicit affected versions

Ubuntu:18.04:LTS linux-hwe-edge

10 explicit affected versions

Ubuntu:18.04:LTS linux-gke-5.4

37 explicit affected versions

Ubuntu:24.04:LTS linux-azure-nvidia

1 explicit affected versions

Ubuntu:22.04:LTS linux-oracle-6.5

13 explicit affected versions

Ubuntu:Pro:FIPS:20.04:LTS linux-aws-fips

1 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.10

26 explicit affected versions

Ubuntu:20.04:LTS linux-gcp-5.13

13 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-aws

144 explicit affected versions

Ubuntu:22.04:LTS linux-xilinx-zynqmp

37 explicit affected versions

Ubuntu:Pro:FIPS:18.04:LTS linux-fips

1 explicit affected versions

Ubuntu:20.04:LTS linux-oem-5.6

29 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-gcp-5.4

111 explicit affected versions

Ubuntu:18.04:LTS linux-gcp-5.3

13 explicit affected versions

Ubuntu:22.04:LTS linux-lowlatency

96 explicit affected versions

Ubuntu:Pro:FIPS:18.04:LTS linux-azure-fips

1 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-raspi-5.4

100 explicit affected versions

Ubuntu:22.04:LTS linux-aws

92 explicit affected versions

Ubuntu:Pro:FIPS-updates:22.04:LTS linux-aws-fips

55 explicit affected versions

Ubuntu:18.04:LTS linux-gke-4.15

33 explicit affected versions

Ubuntu:22.04:LTS linux-riscv

23 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-ibm-5.15

60 explicit affected versions

Ubuntu:18.04:LTS linux-aws-5.3

10 explicit affected versions

Ubuntu:Pro:FIPS-updates:24.04:LTS linux-fips

1 explicit affected versions

Ubuntu:Pro:16.04:LTS linux

188 explicit affected versions

Ubuntu:Nvidia-BlueField:24.04:LTS linux-bluefield

11 explicit affected versions

Ubuntu:20.04:LTS linux-hwe-5.11

12 explicit affected versions

Ubuntu:20.04:LTS linux-azure-5.8

7 explicit affected versions

Ubuntu:22.04:LTS linux-gcp-6.2

12 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-gcp

138 explicit affected versions

Ubuntu:Pro:FIPS:16.04:LTS linux-fips

2 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-kvm

132 explicit affected versions

Ubuntu:22.04:LTS linux-oracle

93 explicit affected versions

Ubuntu:Pro:14.04:LTS linux-lts-xenial

165 explicit affected versions

Ubuntu:Pro:18.04:LTS linux

154 explicit affected versions

Ubuntu:22.04:LTS linux-lowlatency-hwe-5.19

10 explicit affected versions

Ubuntu:22.04:LTS linux-oem-5.17

26 explicit affected versions

Ubuntu:24.04:LTS linux-azure

20 explicit affected versions

Ubuntu:Pro:FIPS-preview:22.04:LTS linux-azure-fips

1 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-intel-iotg-5.15

69 explicit affected versions

Ubuntu:22.04:LTS linux-hwe-6.8

11 explicit affected versions

Ubuntu:24.04:LTS linux-raspi

23 explicit affected versions

Ubuntu:22.04:LTS linux-azure-6.2

13 explicit affected versions

Ubuntu:24.04:LTS linux-ibm

21 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-aws

139 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-ibm-5.4

78 explicit affected versions

Ubuntu:22.04:LTS linux-oem-6.0

16 explicit affected versions

Ubuntu:22.04:LTS linux-kvm

91 explicit affected versions

Ubuntu:24.04:LTS linux-gcp

24 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-aws-hwe

116 explicit affected versions

Ubuntu:22.04:LTS linux-azure-fde-5.19

3 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-azure-5.15

71 explicit affected versions

Ubuntu:22.04:LTS linux-intel-iotg

80 explicit affected versions

Ubuntu:Pro:20.04:LTS linux

132 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-gcp-4.15

93 explicit affected versions

Ubuntu:Pro:FIPS:20.04:LTS linux-azure-fips

1 explicit affected versions

Ubuntu:24.04:LTS linux-gcp-6.11

1 explicit affected versions

Ubuntu:Pro:FIPS-preview:22.04:LTS linux-aws-fips

2 explicit affected versions

Ubuntu:Pro:FIPS-updates:18.04:LTS linux-fips

98 explicit affected versions

Ubuntu:20.04:LTS linux-gke

51 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-azure-4.15

92 explicit affected versions

Ubuntu:24.04:LTS linux-oem-6.11

7 explicit affected versions

Ubuntu:Pro:Realtime:24.04:LTS linux-raspi-realtime

20 explicit affected versions

Ubuntu:20.04:LTS linux-azure-5.13

12 explicit affected versions

Ubuntu:22.04:LTS linux-oem-6.1

27 explicit affected versions

Ubuntu:Nvidia-BlueField:22.04:LTS linux-bluefield

66 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-oracle

121 explicit affected versions

Ubuntu:Pro:FIPS:18.04:LTS linux-aws-fips

1 explicit affected versions

Ubuntu:Pro:FIPS:20.04:LTS linux-fips

1 explicit affected versions

Ubuntu:22.04:LTS linux-hwe-6.5

13 explicit affected versions

Ubuntu:22.04:LTS linux-gcp-5.19

8 explicit affected versions

Ubuntu:Pro:FIPS-updates:22.04:LTS linux-fips

55 explicit affected versions

Ubuntu:20.04:LTS linux-oracle-5.8

5 explicit affected versions

Ubuntu:22.04:LTS linux-riscv-5.19

8 explicit affected versions

Ubuntu:Pro:FIPS:20.04:LTS linux-gcp-fips

1 explicit affected versions

Ubuntu:22.04:LTS linux-hwe-6.2

10 explicit affected versions

Ubuntu:22.04:LTS linux-starfive-5.19

7 explicit affected versions

Ubuntu:Pro:Realtime:24.04:LTS linux-realtime

20 explicit affected versions

Ubuntu:22.04:LTS linux-lowlatency-hwe-6.5

13 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-oracle-5.4

110 explicit affected versions

Ubuntu:20.04:LTS linux-azure-5.11

13 explicit affected versions

Ubuntu:Pro:FIPS-updates:20.04:LTS linux-azure-fips

72 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-azure

140 explicit affected versions

Ubuntu:24.04:LTS linux-nvidia-6.11

2 explicit affected versions

Ubuntu:Pro:FIPS-updates:18.04:LTS linux-aws-fips

94 explicit affected versions

Ubuntu:20.04:LTS linux-riscv-5.8

10 explicit affected versions

Ubuntu:20.04:LTS linux-oracle-5.13

12 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-nvidia-tegra-5.15

39 explicit affected versions

Ubuntu:Pro:18.04:LTS linux-aws-5.4

108 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-bluefield

80 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-xilinx-zynqmp

56 explicit affected versions

Ubuntu:18.04:LTS linux-azure

44 explicit affected versions

Ubuntu:18.04:LTS linux-azure-5.3

16 explicit affected versions

Ubuntu:22.04:LTS linux-starfive-6.2

3 explicit affected versions

Ubuntu:20.04:LTS linux-riscv-5.11

13 explicit affected versions

Ubuntu:20.04:LTS linux-azure-fde

26 explicit affected versions

Ubuntu:20.04:LTS linux-gkeop-5.15

45 explicit affected versions

Ubuntu:18.04:LTS linux-gkeop-5.4

37 explicit affected versions

Ubuntu:24.04:LTS linux-lowlatency

25 explicit affected versions

Ubuntu:22.04:LTS linux-aws-6.5

14 explicit affected versions

Ubuntu:18.04:LTS linux-gcp

38 explicit affected versions

Ubuntu:Pro:16.04:LTS linux-hwe

167 explicit affected versions

Ubuntu:18.04:LTS linux-oracle-5.3

9 explicit affected versions

Ubuntu:22.04:LTS linux-hwe-5.19

11 explicit affected versions

Ubuntu:22.04:LTS linux-riscv-6.8

15 explicit affected versions

Ubuntu:24.04:LTS linux-xilinx

7 explicit affected versions

Ubuntu:22.04:LTS linux-gcp

92 explicit affected versions

Ubuntu:22.04:LTS linux-nvidia-6.2

7 explicit affected versions

Ubuntu:Pro:FIPS:16.04:LTS linux-fips

97 explicit affected versions

Ubuntu:Pro:14.04:LTS linux-azure

121 explicit affected versions

Ubuntu:20.04:LTS linux-gcp-5.8

4 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-riscv-5.15

81 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-aws-5.15

79 explicit affected versions

Ubuntu:24.04:LTS linux-realtime

1 explicit affected versions

Ubuntu:Pro:FIPS-preview:22.04:LTS linux-fips

1 explicit affected versions

Ubuntu:Pro:FIPS-preview:22.04:LTS linux-gcp-fips

1 explicit affected versions

Ubuntu:Pro:Realtime:22.04:LTS linux-realtime

91 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-hwe-5.15

80 explicit affected versions

Ubuntu:18.04:LTS linux-hwe

43 explicit affected versions

Ubuntu:Pro:FIPS-updates:20.04:LTS linux-gcp-fips

77 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-kvm

119 explicit affected versions

Ubuntu:22.04:LTS linux-aws-5.19

10 explicit affected versions

Ubuntu:22.04:LTS linux-allwinner-5.19

8 explicit affected versions

Ubuntu:24.04:LTS linux-gke

19 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-ibm

88 explicit affected versions

Ubuntu:22.04:LTS linux-aws-6.2

14 explicit affected versions

Ubuntu:18.04:LTS linux-azure-edge

4 explicit affected versions

Ubuntu:20.04:LTS linux-gkeop

78 explicit affected versions

Ubuntu:22.04:LTS linux-nvidia-6.5

11 explicit affected versions

Ubuntu:22.04:LTS linux-realtime

1 explicit affected versions

Ubuntu:Pro:FIPS-updates:18.04:LTS linux-gcp-fips

69 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-aws

123 explicit affected versions

Ubuntu:22.04:LTS linux-aws-6.8

14 explicit affected versions

Ubuntu:Pro:20.04:LTS linux-oracle-5.15

80 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

related USN-7276-1
related USN-7277-1

04 / EVIDENCE

Source records

Open Source Vulnerabilities UBUNTU-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.

View original source

05 / REFERENCES

Further evidence