Linux EUVD-2026-81706

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

netdevsim: update queue NAPI association on queue reset

In netdevsim, receive queues (struct nsim_rq) embed their own struct napi_struct. When queue reset is performed (e.g. via queue_reset debugfs), nsim_queue_start() swaps in a newly allocated struct nsim_rq, and nsim_queue_mem_free() later deletes and frees the old one.

However, nsim_queue_start() failed to update the queue-to-NAPI mapping via netif_queue_set_napi(). As a result, dev->_rx[idx].napi continued to point to the old NAPI struct. After the old queue was freed, a subsequent queue dump via Netlink (NETDEV_CMD_QUEUE_GET) triggered a KASAN slab-use-after-free read in nla_put_napi_id() when accessing rxq->napi->napi_id.

Fix this by calling netif_queue_set_napi() in nsim_queue_start() to associate the new NAPI with the RX queue, and clear the association with netif_queue_set_napi(..., NULL) in nsim_del_napi() during teardown.