Linux kernel (arch/x86/kvm): The I/O APIC's delayed EOI work was cancelled only after vCPUs were freed, so the work

Impact

The I/O APIC's delayed EOI work was cancelled only after vCPUs were freed, so the work item can fire against destroyed vCPUs and deliver an interrupt through freed memory. KASAN shows a slab use-after-free read in the APIC fast-delivery path - a host kernel UAF that a local process can schedule at will, which is a privilege-escalation primitive on a shared node.

Who can reach it

Any process that can open /dev/kvm: create a VM with an in-kernel I/O APIC, assert a line so the delayed EOI work is queued, then destroy the VM and let the worker run against the freed vCPUs. No guest cooperation needed beyond running the VM. In a cluster this matters wherever tenants get /dev/kvm directly or via nested virtualization.

What to do

Update to a kernel with the fix (the record lists 6.13 as a fixed release; verify against the referenced commits for your stable branch). Interim: keep /dev/kvm out of tenant containers and disable nested virt for tenant VMs.

References