CVE-2026-74517

Status: UPDATED  |  Advisory ID: CVE-2026-74517

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

KVM: x86: Cancel delayed I/O APIC EOI handling before destroying vCPUs

Cancel (and flush) the I/O APIC's delayed EOI handling work during the

"pre VM destroy" phase, before vCPUs are destroyed, as processing the EOI

broadcast will inject another IRQ if the line is asserted, i.e. will try

to deliver an IRQ to the target vCPU(s). Canceling the work after vCPUs

are destroyed leads to UAF if the delayed work is processed after vCPUs are

destroyed.

BUG: KASAN: slab-use-after-free in __kvm_irq_delivery_to_apic_fast+0x9bf/0xa20 arch/x86/kvm/lapic.c:1250

Read of size 8 at addr ffff8880499abea0 by task kworker/1:2/1218

CPU: 1 UID: 0 PID: 1218 Comm: kworker/1:2 Not tainted 7.1.0-rc7 #5 PREEMPT(lazy)

Hardware name: QEMU Ubuntu 25.10 PC v2 (i440FX + PIIX, + 10.1 machine, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014

Workqueue: events kvm_ioapic_eoi_inject_work

Call Trace:

<TASK>

__dump_stack lib/dump_stack.c:94

dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120

print_address_description mm/kasan/report.c:378

print_report+0x139/0x4ad mm/kasan/report.c:482

kasan_report+0xe4/0x1d0 mm/kasan/report.c:595

__kvm_irq_delivery_to_apic_fast+0x9bf/0xa20 arch/x86/kvm/lapic.c:1250

__kvm_irq_delivery_to_apic+0xd8/0xbf0 arch/x86/kvm/lapic.c:1345

kvm_irq_delivery_to_apic arch/x86/kvm/lapic.h:129

ioapic_service+0x308/0x590 arch/x86/kvm/ioapic.c:492

kvm_ioapic_eoi_inject_work+0x13c/0x190 arch/x86/kvm/ioapic.c:532

process_one_work+0xa59/0x19a0 kernel/workqueue.c:3314

process_scheduled_works kernel/workqueue.c:3397

worker_thread+0x5eb/0xe50 kernel/workqueue.c:3478

kthread+0x370/0x450 kernel/kthread.c:436

ret_from_fork+0x72b/0xd30 arch/x86/kernel/process.c:158

ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

</TASK>

Note, the VM is unreachable once kvm_destroy_vm() starts, and scheduling

new work via kvm_ioapic_send_eoi() can only be done via KVM_RUN, i.e.

requires a live vCPU.

Alternatively, KVM could simply destroy the I/O APIC during the "pre" phase

of VM destruction, but that gets more than a bit sketchy as KVM expects the

I/O APIC to exist if ioapic_in_kernel() is true, and nested virtualization

in particular has a bad habit of touching VM-scope state during vCPU

destruction. E.g. attempting to free the PIC during the pre phase would

lead to a NULL pointer dereference in kvm_cpu_has_extint(), and it's not

hard to imagine the I/O APIC having a similar flaw. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References