CVE-2026-64292iommufd: Move vevent memory allocation outside spinlock

Official description

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 packages & fixed versions

Affected products (as reported)

References

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