Bug 2516581 (CVE-2026-72239)
| Summary: | CVE-2026-72239 kernel: x86/virt/sev: Revert "Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN" | ||
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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: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | unspecified | CC: | rhel-process-autobot, watson-tool-maintainers |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
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| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
A flaw was found in the Linux kernel, specifically within the Secure Encrypted Virtualization-Secure Nested Paging (SEV-SNP) feature. This vulnerability involves a timing issue, or race condition, during the process of clearing processor caches. If not handled correctly, this can lead to a situation where critical memory regions, known as Real Mode Protection (RMP) tables, are not properly synchronized across processors. This failure to synchronize violates fundamental firmware requirements, which could compromise the integrity and security of virtualized environments.
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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: | |||
In the Linux kernel, the following vulnerability has been resolved: x86/virt/sev: Revert "Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN" Revert 99cf1fb58e68 ("x86/virt/sev: Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN"). Section 8.8 of the SNP spec says: Before invoking SNP_INIT_EX with INIT_RMP set to 1, software must ensure that no CPUs contain dirty cache lines for the memory containing the RMP. Cachelines can be moved from cache to cache in a dirty state. The wbinvd_on_all_cpus() before SNP_INIT_EX flushes the caches for each CPU, but if the IPIs for WBINVD race with this dirty cacheline movement, it is possible that they may not get flushed, violating the firmware requirement. Doing wbinvd_on_all_cpus() before setting SNPEn is safer since the RMP table is not yet in use. [ Heroically bisected by Srikanth. ] [ bp: Massage commit message. ]