{"id":"CVE-2026-98841","published":"2026-10-18T16:17:38.417","lastModified":"2026-10-19T10:19:48.197","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvirt: vmgenid: set driver_data before registering notification handlers\n\nBoth probe paths register their notification handler before assigning\ndriver_data, which the handler dereferences.\n\nIn the devicetree path, the notification IRQ can fire as soon as\ndevm_request_irq() registers the handler: the interrupt may already be\npending at probe time, for example when a VMM injects the\ngeneration-changed notification while restoring a guest from a snapshot\nthat was taken before the driver had probed (Firecracker does exactly\nthis on snapshot restore). The IRQ is also requested with IRQF_SHARED,\nso another device sharing the line can trigger the handler just as\nearly. The handler then calls vmgenid_notify(), which dereferences the\nstill-NULL driver_data and panics:\n\n  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010\n  CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.38+ #1 PREEMPT(none)\n  Hardware name: linux,dummy-virt (DT)\n  pc : vmgenid_notify.isra.0+0x24/0x8c\n  lr : vmgenid_of_irq_handler+0x14/0x34\n  Call trace:\n   vmgenid_notify.isra.0+0x24/0x8c (P)\n   vmgenid_of_irq_handler+0x14/0x34\n   __handle_irq_event_percpu+0x44/0x1bc\n   handle_irq_event+0x4c/0xb4\n   handle_fasteoi_irq+0xf8/0x1f8\n\nThe ACPI path has the same ordering problem: the handler is installed\nwith acpi_install_notify_handler() before driver_data is assigned.\nACPI notifications are dispatched asynchronously from a workqueue, so\nthe window is narrow, but a notification arriving between the two calls\nhits the same NULL dereference.\n\nAssign driver_data before registering the handlers. The state is fully\ninitialized at that point, so the handlers are safe to run. Should\nregistration fail, the probe error path leaves no dangling pointer\nbehind: the driver core clears driver_data in device_unbind_cleanup().","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/538fe5efaa9704ad820ba34b4f9df135ca873d79","tags":[]},{"url":"https://git.kernel.org/stable/c/7a1e8daeaa466c6aaffa223e1afe9cfeece0dd47","tags":[]},{"url":"https://git.kernel.org/stable/c/8f42954ad8bf9bdbf574f2c437ad30cb2601f401","tags":[]},{"url":"https://git.kernel.org/stable/c/9f8139c6145cf17d690d6c414d43b4c0bef632fb","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}