In the Linux kernel, the following vulnerability has been resolved:
ipv6: addrconf: bail out of dad_failure when state is no longer POSTDAD
addrconf_dad_failure() transitions ifp->state from DAD to POSTDAD
via addrconf_dad_end(), which drops ifp->lock on return. The lock
is re-acquired after net_info_ratelimited(). A concurrent
ipv6_del_addr() can take the lock in that window, set ifp->state
to DEAD and run list_del_rcu(&ifp->if_list).
addrconf_dad_failure() then overwrites DEAD with ERRDAD at errdad:
and schedules a new dad_work. The work calls ipv6_del_addr()
again, hitting the already-poisoned list entry:
general protection fault: 0000 [#1] SMP NOPTI
CPU: 4 PID: 217 Comm: kworker/4:1
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:ipv6_del_addr+0xe9/0x280
RAX: dead000000000122
Call Trace:
addrconf_dad_stop+0x113/0x140
addrconf_dad_work+0x28c/0x430
process_one_work+0x1eb/0x3b0
worker_thread+0x4d/0x400
kthread+0x104/0x140
ret_from_fork+0x35/0x40
Fold the addrconf_dad_end() logic into addrconf_dad_failure() under
a single ifp->lock critical section. The STABLE_PRIVACY 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.
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 9.8
AV:N - The bug is reached from inbound ICMPv6 Neighbor Discovery (NS/NA) packets processed by icmp6_rcv()→ndisc_rcv()→addrconf_dad_failure(), the standard IPv6 network receive path on internet-facing servers, cloud VMs, phones, and IoT devices on shared L2 segments.
AC:L - An attacker controls both sides of the race by flooding forged NS/NA during DAD while concurrently triggering ipv6_del_addr() via RTM_DELADDR/CAP_NET_ADMIN in a user namespace, CNI/orchestration address teardown, or interface-down processing; retries make the narrow window reliably winnable.
PR:N - Triggering DAD failure requires only unauthenticated ND packet injection on the victim's link; the concurrent ipv6_del_addr() leg needs no victim credentials and can come from automatic address lifecycle events (CNI churn, SLAAC/privacy regeneration, netdev down) rather than attacker admin rights.
UI:N - Exploitation does not require any victim user action such as opening files or mounting filesystems; it targets automatic IPv6 address configuration and DAD processing that occurs during normal network connectivity and boot.
S:U - The corrupted inet6_ifaddr lifecycle and resulting kernel crash occur within kernel memory management; impact does not cross a VM, container, or IOMMU security boundary into a separate authority.
C:H - The race leaves a freed/partially torn-down inet6_ifaddr with corrupted state and a poisoned RCU list entry (LIST_POISON2), constituting use-after-free class memory corruption that can expose adjacent kernel heap contents beyond a pure crash.
I:H - Corrupting inet6_ifaddr state after list_del_rcu() and re-queuing dad_work on a dead object enables heap reuse and control of freed object contents, providing a path to arbitrary kernel memory writes and potential code execution beyond denial of service.
A:H - The demonstrated failure is a general protection fault in ipv6_del_addr() from addrconf_dad_work on the ipv6_addrconf workqueue, causing a kernel oops/panic and complete loss of system availability on affected hosts.
| Attack Vector |
Network |
Scope |
Unchanged |
| Attack Complexity |
Low |
Confidentiality Impact |
High |
| Privileges Required |
None |
Integrity Impact |
High |
| User Interaction |
None |
Availability Impact |
High |
AV:N - The bug is reached from inbound ICMPv6 Neighbor Discovery (NS/NA) packets processed by icmp6_rcv()→ndisc_rcv()→addrconf_dad_failure(), the standard IPv6 network receive path on internet-facing servers, cloud VMs, phones, and IoT devices on shared L2 segments.
AC:L - An attacker controls both sides of the race by flooding forged NS/NA during DAD while concurrently triggering ipv6_del_addr() via RTM_DELADDR/CAP_NET_ADMIN in a user namespace, CNI/orchestration address teardown, or interface-down processing; retries make the narrow window reliably winnable.
PR:N - Triggering DAD failure requires only unauthenticated ND packet injection on the victim's link; the concurrent ipv6_del_addr() leg needs no victim credentials and can come from automatic address lifecycle events (CNI churn, SLAAC/privacy regeneration, netdev down) rather than attacker admin rights.
UI:N - Exploitation does not require any victim user action such as opening files or mounting filesystems; it targets automatic IPv6 address configuration and DAD processing that occurs during normal network connectivity and boot.
S:U - The corrupted inet6_ifaddr lifecycle and resulting kernel crash occur within kernel memory management; impact does not cross a VM, container, or IOMMU security boundary into a separate authority.
C:H - The race leaves a freed/partially torn-down inet6_ifaddr with corrupted state and a poisoned RCU list entry (LIST_POISON2), constituting use-after-free class memory corruption that can expose adjacent kernel heap contents beyond a pure crash.
I:H - Corrupting inet6_ifaddr state after list_del_rcu() and re-queuing dad_work on a dead object enables heap reuse and control of freed object contents, providing a path to arbitrary kernel memory writes and potential code execution beyond denial of service.
A:H - The demonstrated failure is a general protection fault in ipv6_del_addr() from addrconf_dad_work on the ipv6_addrconf workqueue, causing a kernel oops/panic and complete loss of system availability on affected hosts.
CVSS 3.1