Bug 2315216 (CVE-2024-46864)
| Summary: | CVE-2024-46864 kernel: x86/hyperv: fix kexec crash due to VP assist page corruption | ||
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| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | low | Docs Contact: | |
| Priority: | low | ||
| Version: | unspecified | CC: | dfreiber, drow, jburrell, vkumar |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: |
in cpuhp_setup_state() a requisite condition of "hyperv_init_cpuhp > 0" for the hyperv case will never be true, and then hv_cpu_die() won't be called on all CPUs and the VP assist page will not be reset. This leads to corruption of the previous VP assist page and ultimately panic if the kexec kernel is using that memory. The hyperv_init_cpuhp condition should be removed entirely.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | 2315239 | ||
| Bug Blocks: | |||
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2024092745-CVE-2024-46864-0343@gregkh/T This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2025:6966 https://access.redhat.com/errata/RHSA-2025:6966 |
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().