Findings

CVE-2026-74568

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: vgic: Fix race between LPI release and re-registration Fix a potential race between dec…

Published Aug 15, 2026 · updated Oct 15, 2026

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: vgic: Fix race between LPI release and re-registration Fix a potential race between decrementing an LPI's reference count and evicting that structure from the LPI xarray. LPI structures are maintained in the VGIC LPI xarray (dist->lpi_xa). When the reference count of an LPI structure drops to zero, vgic_release_lpi_locked() removes the structure from the xarray and frees it under the xarray lock. However, the release of an LPI can race with a concurrent LPI re-registration with the same INTID via vgic_add_lpi() on another CPU, since the reference count drop and the xarray eviction are not performed in a single atomic step. This can happen e.g. if the guest issues a DISCARD while the LPI is still referenced from a vCPU's active-pending list (ap_list), and the same INTID is re-mapped via MAPTI. Particularly, vgic_release_lpi_locked() is called from two distinct paths: direct release via vgic_put_irq(), and deferred release via vgic_release_deleted_lpis(). During direct release, the issue can result in deleting a newly registered LPI from the xarray: CPU0 (Releasing LPI) CPU1 (Adding new LPI) ==================== ===================== vgic_put_irq() __vgic_put_irq() refcount_dec_and_test() vgic_add_lpi() xa_lock_irqsave() old_irq = xa_load(.., intid) vgic_try_get_irq_ref(old_irq) == false new IRQ inserted --> __xa_store(.., intid, ..) xa_unlock_irqrestore() xa_lock_irqsave(); vgic_release_lpi_locked() __xa_erase(.., irq->intid) pending_release = true vgic_add_lpi() xa_lock_irqsave() old_irq = xa_load(.., intid) vgic_try_get_irq_ref(oldirq) == false BUG: old IRQ overwritten --> __xa_store(.., intid, ..) xa_unlock_irqrestore() vgic_release_deleted_lpis() xa_lock_irqsave() xa_for_each() { .. } <-- old IRQ with pending_release = true is gone, so it cannot be released To fix the direct release path, move the reference count drop inside the xarray lock, making sure that vgic_add_lpi() never encou