From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 03FC940587A; Tue, 21 Jul 2026 17:43:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784655817; cv=none; b=gNcGpB367yAXd+BJYeK6ZnkooA8LPaiY5bV1o/y3x7NRDfk3i94WpkmFoJP7tOxnXli47827kbZkCyG98ci6A7LyLrYoYm19F7o4iavy33Xdi1hmiqBttTYPT15W6JeUKLaleSbxkUVlsw4uuCCgzXWYnWKaOufYZ8TESlRo+UA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784655817; c=relaxed/simple; bh=KBiOG2RBwsKVWQVGKyf5ixGYqJW/33QIQo+BjQVCT9U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KDBSF3anabMzRacbd87XifQcudvlrHhqx/YEMeAN6noJrzaIXyv7KBdL+o6lGTswqiHvJYw2R3/RLw4BwjLFrYyqp2udC43Uy+gdLre9XmJtaRXm+6QvgHxOTOTD+nIQyUFVPOZ5xOkCQx94hsqvd4s1g8Ipha49wwbrTfCsEDM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=TojRNy0Z; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="TojRNy0Z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B9D01F00A3A; Tue, 21 Jul 2026 17:43:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784655815; bh=0vwEpL2iXApT/dRawl3P8lp7x3lAfE8m/k1U/PW/Mko=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=TojRNy0Zys4FD+ZKri9ZrPiUEwPFd+uR+zUnuEu5HmmYmL7c/qpNmJv+S7SzG4t8I bZelRt0gcLY8E+wflp4T7pyUEQn1mfJ2RTHjoZJjQOEyL7ivb7gLTVm1OUrAH/r3/P suEPq278r5/l0H4vpebVLHtCD+p0m8tFKMiNUQUk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Linmao Li , Ido Schimmel , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 0153/1611] ipv6: addrconf: bail out of dad_failure when state is no longer POSTDAD Date: Tue, 21 Jul 2026 17:04:29 +0200 Message-ID: <20260721152518.320849356@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Linmao Li [ Upstream commit 627ac78f2741e2ebd2225e2e953b6964a8a9182f ] 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 Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260513025509.3776405-1-lilinmao@kylinos.cn Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- 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 b2e1328371d3f6..c8c82891fe14c9 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -2168,16 +2168,18 @@ void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp) struct net *net = dev_net(idev->dev); int max_addresses; - 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; @@ -2225,6 +2227,11 @@ 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: -- 2.53.0