UBUNTU-CVE-2026-80858

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UBUNTU-CVE-2026-80858

Summary:

Details: In the Linux kernel, the following vulnerability has been resolved: fuse: publish io-uring queues with release semantics fuse_uring_create_queue() initializes a fuse_ring_queue and then publishes the pointer into ring->queues[qid] with WRITE_ONCE() under the fch->lock. There are several readers that may concurrently be fetching that pointer locklessly and then deferencing it. WRITE_ONCE() doesn't ensure ordering of the queue's field initialization before the ring->queues[qid] pointer assignment. The queue must be published with smp_store_release() so the field initialization is guaranteed to happen before. Readers in paths where the read may happen concurrently with the store need to use READ_ONCE() because any race involving a plain access is undefined.

References: https://ubuntu.com/security/CVE-2026-80858, https://www.cve.org/CVERecord?id=CVE-2026-80858, https://git.kernel.org/linus/42df916e5a5f8fb4b60c8cefb54318d1ec02c580