CVE-2026-74398 ipv6: addrconf: bail out of dad_failure when state is no longer POSTDAD

In the Linux kernel, the following vulnerability has been resolved: ipv6: addrconf: bail out of dadfailure when state is no longer POSTDAD addrconfdadfailure transitions ifp-state from DAD to POSTDAD via addrconfdadend, which drops ifp-lock on return. The lock is re-acquired after...