Linux Kernel Vulnerability Affecting KVM Functionality

CVE-2026-89775

What is CVE-2026-89775?

The vulnerability found in the Linux kernel relates to KVM's handling of negative S1 walk levels during TLB size calculation. Specifically, when the MMU is disabled, a negative level (-127) causes misinterpretation in the pgshift_level_to_ttl() function, leading to incorrect TLB invalidation sizes. This flaw compromises the functionality and security of virtualization on arm64 architectures. Developers have made adjustments to the affected functions to properly account for these negative levels, improving the overall robustness of the kernel's KVM behavior.

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