CVE-2026-80859

Summary

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

fuse: fix missing barrier when checking io-uring readiness

fuse_block_alloc() reads fch->initialized and then fch->io_uring. fch->io_uring is set before fch->initialized, ordered by the smp_wmb() in fuse_chan_set_intialized(), but fuse_block_alloc() has no matching read barrier between the two loads.

This may lead a CPU to observe fch->initialized=1 but fch->io_uring=0, and skip the check that blocks request allocation until the io-uring queues are ready. This can reintroduce the lock-order inversion deadlock that commit 3393ff964e0f prevents.

Add an smp_rmb() barrier to pair with the smp_wmb() in fuse_chan_set_initialized() to prevent this.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/dd9c835709f4bb3e4256eea7573e4e6e18f956de
• https://git.kernel.org/stable/c/edb310bc27f0ad83e7fd558a3caf1a94ca511654

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