In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Don't retire aborted MMIO instruction
Returning an abort to the guest for an unsupported MMIO access is a
documented feature of the KVM UAPI. Nevertheless, it's clear that this
plumbing has seen limited testing, since userspace can trivially cause a
WARN in the MMIO return:
WARNING: CPU: 0 PID: 30558 at arch/arm64/include/asm/kvm_emulate.h:536 kvm_handle_mmio_return+0x46c/0x5c4 arch/arm64/include/asm/kvm_emulate.h:536
Call trace:
kvm_handle_mmio_return+0x46c/0x5c4 arch/arm64/include/asm/kvm_emulate.h:536
kvm_arch_vcpu_ioctl_run+0x98/0x15b4 arch/arm64/kvm/arm.c:1133
kvm_vcpu_ioctl+0x75c/0xa78 virt/kvm/kvm_main.c:4487
__do_sys_ioctl fs/ioctl.c:51 [inline]
__se_sys_ioctl fs/ioctl.c:893 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:893
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
el0_svc_common+0x1e0/0x23c arch/arm64/kernel/syscall.c:132
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
el0_svc+0x38/0x68 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x90/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
The splat is complaining that KVM is advancing PC while an exception is
pending, i.e. that KVM is retiring the MMIO instruction despite a
pending synchronous external abort. Womp womp.
Fix the glaring UAPI bug by skipping over all the MMIO emulation in
case there is a pending synchronous exception. Note that while userspace
is capable of pending an asynchronous exception (SError, IRQ, or FIQ),
it is still safe to retire the MMIO instruction in this case as (1) they
are by definition asynchronous, and (2) KVM relies on hardware support
for pending/delivering these exceptions instead of the software state
machine for advancing PC.
Metrics
Affected Vendors & Products
References
History
Mon, 30 Dec 2024 01:30:00 +0000
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cvssV3_1
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Fri, 27 Dec 2024 14:00:00 +0000
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Description | In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Don't retire aborted MMIO instruction Returning an abort to the guest for an unsupported MMIO access is a documented feature of the KVM UAPI. Nevertheless, it's clear that this plumbing has seen limited testing, since userspace can trivially cause a WARN in the MMIO return: WARNING: CPU: 0 PID: 30558 at arch/arm64/include/asm/kvm_emulate.h:536 kvm_handle_mmio_return+0x46c/0x5c4 arch/arm64/include/asm/kvm_emulate.h:536 Call trace: kvm_handle_mmio_return+0x46c/0x5c4 arch/arm64/include/asm/kvm_emulate.h:536 kvm_arch_vcpu_ioctl_run+0x98/0x15b4 arch/arm64/kvm/arm.c:1133 kvm_vcpu_ioctl+0x75c/0xa78 virt/kvm/kvm_main.c:4487 __do_sys_ioctl fs/ioctl.c:51 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:893 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x1e0/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x38/0x68 arch/arm64/kernel/entry-common.c:712 el0t_64_sync_handler+0x90/0xfc arch/arm64/kernel/entry-common.c:730 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598 The splat is complaining that KVM is advancing PC while an exception is pending, i.e. that KVM is retiring the MMIO instruction despite a pending synchronous external abort. Womp womp. Fix the glaring UAPI bug by skipping over all the MMIO emulation in case there is a pending synchronous exception. Note that while userspace is capable of pending an asynchronous exception (SError, IRQ, or FIQ), it is still safe to retire the MMIO instruction in this case as (1) they are by definition asynchronous, and (2) KVM relies on hardware support for pending/delivering these exceptions instead of the software state machine for advancing PC. | |
Title | KVM: arm64: Don't retire aborted MMIO instruction | |
References |
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Status: PUBLISHED
Assigner: Linux
Published: 2024-12-27T13:49:38.501Z
Updated: 2025-01-20T06:21:02.413Z
Reserved: 2024-11-19T17:17:25.015Z
Link: CVE-2024-53196

No data.

Status : Received
Published: 2024-12-27T14:15:27.267
Modified: 2024-12-27T14:15:27.267
Link: CVE-2024-53196
