From: Linmao Li <lilinmao@kylinos.cn> mainline inclusion from mainline-v7.2-rc1 commit 627ac78f2741e2ebd2225e2e953b6964a8a9182f category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18025 CVE: CVE-2026-74398 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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. Fixes: c15b1ccadb32 ("ipv6: move DAD and addrconf_verify processing to workqueue") Signed-off-by: Linmao Li <lilinmao@kylinos.cn> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20260513025509.3776405-1-lilinmao@kylinos.cn Signed-off-by: Jakub Kicinski <kuba@kernel.org> Conflicts: net/ipv6/addrconf.c [Contextual differences between the branch and mainline required adaptation during patch application. The functional changes from the upstream commit are preserved.] Signed-off-by: JiangJieHua <jiangjiehua1@huawei.com> --- net/ipv6/addrconf.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 98a24b5e6f036..7b8dda47d3855 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -2020,16 +2020,18 @@ void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp) struct inet6_dev *idev = ifp->idev; struct net *net = dev_net(ifp->idev->dev); - if (addrconf_dad_end(ifp)) { + spin_lock_bh(&ifp->lock); + + if (ifp->state != INET6_IFADDR_STATE_DAD) { + spin_unlock_bh(&ifp->lock); in6_ifa_put(ifp); return; } + ifp->state = INET6_IFADDR_STATE_POSTDAD; net_info_ratelimited("%s: IPv6 duplicate address %pI6c used by %pM detected!\n", ifp->idev->dev->name, &ifp->addr, eth_hdr(skb)->h_source); - spin_lock_bh(&ifp->lock); - if (ifp->flags & IFA_F_STABLE_PRIVACY) { struct in6_addr new_addr; struct inet6_ifaddr *ifp2; @@ -2077,6 +2079,11 @@ void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp) in6_ifa_put(ifp2); lock_errdad: spin_lock_bh(&ifp->lock); + if (ifp->state != INET6_IFADDR_STATE_POSTDAD) { + spin_unlock_bh(&ifp->lock); + in6_ifa_put(ifp); + return; + } } errdad: -- 2.33.8