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 502B3379960; Tue, 21 Jul 2026 23:00:44 +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=1784674845; cv=none; b=nK6CiF0YuPmecO2JIXwHKpxlF3uFa5OLHKWaSRemGY2uOWIu4IAIDBfU6YLsExT1gXajRuJQzaFSwmvZvqdAAYGg51pRFrDg02X23/22OewK1ZzDDO0kJazQ/YAn1krr+aCS0C0AmDnGEajOgRnVft7WB+pbhuINIGaDo999GxU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784674845; c=relaxed/simple; bh=tl8+9shVT6edxN8Wv/nBxean06oDQyH3OGSfNKqE/qw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DkhCMQpp986AxGaukRGKLloFWgKmaoKoPq6t9hQdWuIgLsQ0Q1qulph3Z3rxsQB6RCVrkyojQoEsyQV25eEaWP0tuz5kidz9hUThC9oFksG8pwnofNgvLGtYtKYt1ZXqLzngFfDbJCL0jY5OZw77xrD4rG+Fh95/GFeYy4lFxBs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FY51d2CQ; 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="FY51d2CQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B59DD1F000E9; Tue, 21 Jul 2026 23:00:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784674844; bh=eqvXvmWORp8Rey7D7CZBeHyiIKL4bbYKN+5sYuim7Lw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=FY51d2CQvAPQlo8TwCEWCG3ecNrNSG4VyCFoIA3Prs+hEow+NzVqG7D7fBScCzkaj HNC3rx8TixK598G5C8+NgEJq7UXytANCxMC8Movh90q1uFZpE2Mcg+4FhVjJs9Rfcn qL1RXc5Fu7JtEDSR+4P+6yzN5b72D/hnjimRLYgE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot , Eric Dumazet , Taehee Yoo , Jakub Kicinski Subject: [PATCH 5.10 695/699] ipv6: fix lockdep splat in in6_dump_addrs() Date: Tue, 21 Jul 2026 17:27:34 +0200 Message-ID: <20260721152411.456933398@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152355.667394603@linuxfoundation.org> References: <20260721152355.667394603@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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 4e43e64d0f1332fcc503babad4dc31aead7131ca upstream. As reported by syzbot, we should not use rcu_dereference() when rcu_read_lock() is not held. WARNING: suspicious RCU usage 5.19.0-rc2-syzkaller #0 Not tainted net/ipv6/addrconf.c:5175 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by syz-executor326/3617: #0: ffffffff8d5848e8 (rtnl_mutex){+.+.}-{3:3}, at: netlink_dump+0xae/0xc20 net/netlink/af_netlink.c:2223 stack backtrace: CPU: 0 PID: 3617 Comm: syz-executor326 Not tainted 5.19.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 in6_dump_addrs+0x12d1/0x1790 net/ipv6/addrconf.c:5175 inet6_dump_addr+0x9c1/0xb50 net/ipv6/addrconf.c:5300 netlink_dump+0x541/0xc20 net/netlink/af_netlink.c:2275 __netlink_dump_start+0x647/0x900 net/netlink/af_netlink.c:2380 netlink_dump_start include/linux/netlink.h:245 [inline] rtnetlink_rcv_msg+0x73e/0xc90 net/core/rtnetlink.c:6046 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:734 ____sys_sendmsg+0x6eb/0x810 net/socket.c:2492 ___sys_sendmsg+0xf3/0x170 net/socket.c:2546 __sys_sendmsg net/socket.c:2575 [inline] __do_sys_sendmsg net/socket.c:2584 [inline] __se_sys_sendmsg net/socket.c:2582 [inline] __x64_sys_sendmsg+0x132/0x220 net/socket.c:2582 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 Fixes: 88e2ca308094 ("mld: convert ifmcaddr6 to RCU") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Taehee Yoo Link: https://lore.kernel.org/r/20220628121248.858695-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ipv6/addrconf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -5178,9 +5178,9 @@ next: fillargs->event = RTM_GETMULTICAST; /* multicast address */ - for (ifmca = rcu_dereference(idev->mc_list); + for (ifmca = rtnl_dereference(idev->mc_list); ifmca; - ifmca = rcu_dereference(ifmca->next), ip_idx++) { + ifmca = rtnl_dereference(ifmca->next), ip_idx++) { if (ip_idx < s_ip_idx) continue; err = inet6_fill_ifmcaddr(skb, ifmca, fillargs);