DEBIAN-CVE-2026-74398

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 netinforatelimited().  A concurrent ipv6deladdr() can take the lock in that window, set ifp->state to DEAD and run listdelrcu(&ifp->iflist).  addrconfdadfailure() then overwrites DEAD with ERRDAD at errdad: and schedules a new dadwork.  The work calls ipv6deladdr() again, hitting the already-poisoned list entry:    general protection fault: 0000 [#1] SMP NOPTI   CPU: 4 PID: 217 Comm: kworker/4:1   Workqueue: ipv6addrconf addrconfdadwork   RIP: 0010:ipv6deladdr+0xe9/0x280   RAX: dead000000000122   Call Trace:    addrconfdadstop+0x113/0x140    addrconfdadwork+0x28c/0x430    processonework+0x1eb/0x3b0    workerthread+0x4d/0x400    kthread+0x104/0x140    retfromfork+0x35/0x40  Fold the addrconfdadend() logic into addrconfdadfailure() under a single ifp->lock critical section.  The STABLEPRIVACY branch temporarily drops ifp->lock around address regeneration, so at lock_errdad: verify the state is still POSTDAD before transitioning to ERRDAD; bail out otherwise to avoid overwriting a state set by another path while the lock was released.