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 60EAA4A8430; Wed, 30 Sep 2026 18:28:40 +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=1790792921; cv=none; b=OYj7V3+265kkz/OwF+kz4cAZi8Ea/4GAj3FFpxqRIqTetH6sQY5q40d26d4Kt0aV9ggrkGxm80PS1uBHLrtr4Y2kBNy1q1H3buuvF+yPZuG988P7VIowNCmgStUX0kqmFMetOKP4EVc4DYt35RmueSNbVoiYmCM6mAEhuiqiFq4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790792921; c=relaxed/simple; bh=kpfQYmOXgVFrvsd17DNSAlcaST5VkVMslD828lpxyvI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=snbLQ6FDNs83+Dj+YD/bWJGuszrPGl/7GPsWVZMtSKKw/glz/BtkU2f4tK7VhzfS8jOpJNNvUNp4lMVvkixY87NJbmbta/rJAvxK0evjaZavShMDVEW3IU1zU2wQFvAmbaD2d/8OGb1b2bfv8S4QR8ANQAU4L5A7wGImweiGUWw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=y0b89RGc; 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="y0b89RGc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 467041F000FF; Wed, 30 Sep 2026 18:28:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790792919; bh=+WjdnZuBzTH8J2SNCM2nN6HlxmsXG4CknZN+BPQ75ME=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=y0b89RGcHkg9ebekJMLyBnjZDmvi9SY/VEA69oaNGWeoAGEEiRz8Pbe+3XgKpYe65 uzUpAZigmZ4jPiHQ0kDfT502/yfI7AnwpEm2GP9K7h7q2UuKfuFVhrGhEFeEe4IV+a kWLvZoAj7Fpo3FB2jkJr3dUO0A0OX5v4WE9h6TAk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+4bd730aede2791e40bdf@syzkaller.appspotmail.com, Naman Gulati , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.18 070/395] netfilter: ctnetlink: fix suspicious RCU usage in expect_iter_name Date: Wed, 30 Sep 2026 17:25:32 +0200 Message-ID: <20260930152342.157116491@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152340.591469096@linuxfoundation.org> References: <20260930152340.591469096@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: Naman Gulati [ Upstream commit 207d591c353201f3bd3e0c89bb7d44a849c8fd59 ] expect_iter_name() is invoked by nf_ct_expect_iterate_net() under spin_lock_bh(&nf_conntrack_expect_lock). It does not hold rcu_read_lock(). When accessing exp->helper with rcu_dereference() in syzbot's report, lockdep warns: ============================= WARNING: suspicious RCU usage syzkaller #0 Not tainted ----------------------------- net/netfilter/nf_conntrack_netlink.c:3393 suspicious rcu_dereference_check() usage! locks held by syz-executor381/5628: 2, last CPU#1: #0: ffffffff9aee42a0 (nfnl_subsys_ctnetlink_exp){+.+.}-{4:4}, at: nfnetlink_rcv_msg+0xa69/0x12b0 #1: ffffffff8ea74d58 (nf_conntrack_expect_lock){+...}-{3:3}, at: nf_ct_expect_iterate_net+0x38/0x180 Call Trace: dump_stack_lvl+0xe8/0x150 lockdep_rcu_suspicious+0x140/0x1d0 expect_iter_name+0xfb/0x100 nf_ct_expect_iterate_net+0xf2/0x180 ctnetlink_del_expect+0x45d/0x640 nfnetlink_rcv_msg+0xcc2/0x12b0 netlink_rcv_skb+0x226/0x4a0 nfnetlink_rcv+0x2b9/0x28c0 netlink_unicast+0x7bd/0x940 netlink_sendmsg+0x813/0xb40 ____sys_sendmsg+0x54e/0x850 ___sys_sendmsg+0x2a5/0x360 __sys_sendmsg+0x2a5/0x360 do_syscall_64+0x166/0x520 entry_SYSCALL_64_after_hwframe+0x77/0x7f Use rcu_dereference_protected() with lockdep_is_held() on nf_conntrack_expect_lock instead, similar to expect_iter_me() in nf_conntrack_helper.c. Fixes: f01794106042 ("netfilter: nf_conntrack_expect: use expect->helper") Reported-by: syzbot+4bd730aede2791e40bdf@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6aa4a377.f81106d8.2ab401.0024.GAE@google.com/T/#u Signed-off-by: Naman Gulati Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_conntrack_netlink.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 48cf3dad61bdb..5211599357189 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -3395,7 +3395,8 @@ static bool expect_iter_name(struct nf_conntrack_expect *exp, void *data) struct nf_conntrack_helper *helper; const char *name = data; - helper = rcu_dereference(exp->helper); + helper = rcu_dereference_protected(exp->helper, + lockdep_is_held(&nf_conntrack_expect_lock)); if (!helper) return false; -- 2.53.0