CVE-2025-21857 net/sched: cls_api: fix error handling causing NULL dereference

In the Linux kernel, the following vulnerability has been resolved: net/sched: clsapi: fix error handling causing NULL dereference tcfextsmisscookiebasealloc calls xaalloccyclic which can return 1 if the allocation succeeded after wrapping. This was treated as an error, with value 1 returned to...