Linux kernel (drivers/pci/endpoint): The endpoint function core calls list_del() on a structure that is a list HEAD

Impact

The endpoint function core calls list_del() on a structure that is a list HEAD, not a list entry, so tearing down an endpoint function driver writes two pointers into memory that has already been freed. KASAN reports it as a slab use-after-free write - an attacker-useful primitive, not just a crash, if the freed slab has been reallocated.

Who can reach it

Endpoint mode required. Triggered by unloading an endpoint function driver that registered a configfs attribute group; the upstream KASAN splat came from unloading nvmet_pci_epf, the NVMe-over-PCIe endpoint target. That is host root on the endpoint machine, not a tenant action - but nvmet_pci_epf is exactly the kind of tenant-facing storage target a provider would run on an endpoint device, and its module lifecycle is part of normal service management.

What to do

Update to a kernel carrying the fix (no fixed_in published; stable commits below). Interim: do not unload endpoint function driver modules on a live system - especially nvmet_pci_epf - and reboot to change endpoint function configuration.

References