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 DBB001D7E5C; Tue, 21 Jul 2026 20:28:33 +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=1784665715; cv=none; b=SzBperQdBcFZFyfJ0ybVBW632+Zx90HLq4c7M1xOnKEULBi6twmO7qezS6V2b5646fwUlxhw/oIrn5rSR/s0I5oXVeDQHxeWjl7kLkIgsHSZiHhTPiUxa1g+iziY4pdtA+HnyXUte4pxI/mQumSycjjXsstbUsEEY/PO3tZ5o0w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784665715; c=relaxed/simple; bh=s8weQ9Fy126ZW/XVClC+ZDfPhunsSVBGw//RsoASCh8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kfzvuk5jBbdDVmzMFr7XKK+GKtx5ISYRcWNUqP/LRCcEOSdPe3x8n4Av7rk5dmyT7DBFPVp4M94/uvx5yemgbLaejrkGiGlmCRb3L/lvIDuskHJ3G8e6MtBDXOENoDyFDtKPGA0C6H/HuulC93IISmKcoHFaPoslUj9n4FjwQRM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h1U6iaBP; 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="h1U6iaBP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 129D21F000E9; Tue, 21 Jul 2026 20:28:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784665713; bh=Vit6pCpeePMglMbPHFF9eUavbpFlpCgmiTporF3UfHg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=h1U6iaBPA/LnZ5om5NGOcvpDwL1CvoW4oD3uSugb51xFis+6AvOuAK7AK2MtsOYQW SnywpaJK8f0anT8n9YZcPhUjBI6gLyerzAHk/hD/cxdpSecyzxLgOSdmZmTHydWZW5 EIghra5BBefkPiD1gSFgjP7H+/t9r2WpNvxLXETg= 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 6.6 0406/1266] ipv6: addrconf: bail out of dad_failure when state is no longer POSTDAD Date: Tue, 21 Jul 2026 17:14:03 +0200 Message-ID: <20260721152450.920057678@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152441.786066624@linuxfoundation.org> References: <20260721152441.786066624@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 6.6-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 d752776da51fd8..5f32793a29eafa 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -2138,16 +2138,18 @@ void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp) struct inet6_dev *idev = ifp->idev; struct net *net = dev_net(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; @@ -2195,6 +2197,11 @@ 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