CVE-2024-46864 x86/hyperv: fix kexec crash due to VP assist page corruption

What is CVE-2024-46864?

CVE-2024-46864 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Sep 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

x86/hyperv: fix kexec crash due to VP assist page corruption

commit 9636be85cc5b ("x86/hyperv: Fix hyperv_pcpu_input_arg handling when CPUs go online/offline") introduces a new cpuhp state for hyperv initialization.

cpuhp_setup_state() returns the state number if state is CPUHP_AP_ONLINE_DYN or CPUHP_BP_PREPARE_DYN and 0 for all other states. For the hyperv case, since a new cpuhp state was introduced it would return 0. However, in hv_machine_shutdown(), the cpuhp_remove_state() call is conditioned upon "hyperv_init_cpuhp > 0". This will never be true and so hv_cpu_die() won't be called on all CPUs. This means the VP assist page won't be reset. When the kexec kernel tries to setup the VP assist page again, the hypervisor corrupts the memory region of the old VP assist page causing a panic in case the kexec kernel is using that memory elsewhere. This was originally fixed in commit dfe94d4086e4 ("x86/hyperv: Fix kexec panic/hang issues").

Get rid of hyperv_init_cpuhp entirely since we are no longer using a dynamic cpuhp state and use CPUHP_AP_HYPERV_ONLINE directly with cpuhp_remove_state().

Which versions are affected by CVE-2024-46864?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-46864?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2024-46864 being exploited?

There is no known exploitation of CVE-2024-46864 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-49900, BELL-CVE-2024-46864, DEBIAN-CVE-2024-46864, GHSA-7555-3222-qmcm, UBUNTU-CVE-2024-46864.