CVE-2026-64292

Summary

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

iommufd: Move vevent memory allocation outside spinlock

The veventq memory allocation happens inside the spinlock. Given its depth is decided by the user space, this leaves a vulnerability, where userspace can allocate large queues to exhaust atomic memory reserves.

Move the allocation outside the spinlock and use GFP_NOWAIT, which can fail fast under memory pressure without dipping into the GFP_ATOMIC reserves or direct-reclaiming from the threaded IRQ handler. On allocation failure, queue the lost_events_header (so userspace learns of the drop) and return -ENOMEM so the caller learns of the kernel-side memory pressure.

This is intentionally distinct from the queue-overflow path, which also queues the lost_events_header but returns 0: a full queue is an expected userspace-pacing condition rather than a kernel error.

A subsequent change will cap the upper bound of the veventq_depth.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/779480ea79551c31964e74b9aef0e730faa3aa11
• https://git.kernel.org/stable/c/6c5fc40200cd0a87d66a368eee00df4d1cca946e
• https://git.kernel.org/stable/c/47443565d10c51366c9382dbc8597cd6c460b8a2

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