CVE-2025-68245CVE-2025-68245

In the Linux kernel, the following vulnerability has been resolved: net: netpoll: fix incorrect refcount handling causing incorrect cleanup commit efa95b01da18 ("netpoll: fix use after free") incorrectly ignored the refcount and prematurely set dev->npinfo to NULL during netpoll cleanup, leading to improper behavior and memory leaks. Scenario causing lack of proper cleanup: 1) A netpoll is associated with a NIC (e.g., eth0) and netdev->npinfo is allocated, and refcnt = 1 - Keep in mind that npinfo is shared among all netpoll instances. In this case, there is just one. 2) Another netpoll is also associated with the same NIC and npinfo->refcnt += 1. - Now dev->npinfo->refcnt = 2; - There is just one npinfo associated to the netdev. 3) When the first netpolls goes to clean up: - The first cleanup succeeds and clears np->dev->npinfo, ignoring refcnt. - It basically calls `RCU_INIT_POINTER(np->dev->npinfo, NULL);` - Set dev->npinfo = NULL, without p