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 proper cleanup
- No ->ndonetpollcleanup() is either called
4) Now the second target tries to clean up - The second cleanup fails because np->dev->npinfo is already NULL. * In this case, ops->ndonetpollcleanup() was never called, and the skb pool is not cleaned as well (for the second netpoll instance) - This leaks npinfo and skbpool skbs, which is clearly reported by kmemleak.
Revert commit efa95b01da18 ("netpoll: fix use after free") and adds clarifying comments emphasizing that npinfo cleanup should only happen once the refcount reaches zero, ensuring stable and correct netpoll behavior.
{
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68245.json",
"cna_assigner": "Linux"
}