CVE-2026-64588

In the Linux kernel, the following vulnerability has been resolved:

fuse-uring: fix data races on ring->ready

On weakly-ordered architectures, the store to fiq->ops can be reordered past the store to ring->ready, allowing a CPU that sees ring->ready == true via fuseuringready() to dispatch requests through a stale fiq->ops pointer. Upgrade the store to smpstorerelease() and the load in fuseuringready() to smploadacquire() so that the preceding WRITE_ONCE(fiq->ops, ...) is visible to any CPU that observes ring->ready == true.

Additionally, fuseuringdoregister() publishes ring->ready with WRITEONCE() but the fast-path check reads it with a plain load. This is a marked-vs-unmarked access that KCSAN will flag. Wrap it in READ_ONCE() to mark it without adding unnecessary ordering.

Also wrap the fc->ring load in fuseuringready() in READ_ONCE() to prevent the compiler from reloading it between the NULL check and the dereference.