Concurrency Vulnerability in Linux Kernel Affecting Hypervisor Implementations

CVE-2026-80895

What is CVE-2026-80895?

A concurrency vulnerability has been identified in the Linux kernel's handling of virtual partitions within hypervisor implementations. Specifically, the issue arises when a virtual processor (VP) structure is initialized and its pointer is published to an array, allowing for potential race conditions during concurrent access. The mshv_try_assert_irq_fast function can read from this array without proper locking, leading to the possibility of observing partially initialized VP structures. This can result in undefined behaviors as certain fields may not be correctly populated when accessed. To mitigate this issue, proper memory barriers (smp_store_release and smp_load_acquire) were introduced to ensure safe publication and access of VP structures, preventing the race condition and enhancing the integrity of hypervisor operations.

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