From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 458E42C032E for ; Sat, 12 Sep 2026 01:11:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789175481; cv=none; b=HAmFpEN9sMsk+JEfRMnSkpXn/F6NSljoajpN0oBg8q/HTffMJmnf7YhFdfA8iLNU6m/Sp+OYP5TSjZbG2a9J7F2fxoGbnw1ZL55+Y6xt6Xoc80PxH0U/6QANmK5iCGgsRt9ZzNk7IyCs6f+n+wUUDdeeQRr50AZBU68Uw672nvE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789175481; c=relaxed/simple; bh=eMB6tvT0hZZyGsnNThdI/TAeAqIFVfVoL7cYicGIp54=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=HpGWyuSZX+TPOHtM+f74iescBn3whf6OzWaFhscylXE0XOD3MYOZG4z2TeKbjdRou1RlixuZqC555yo+COPhc94K7S86vigL/W3QYNRAazybh+We341c8vKOCQzcFdL4n1CamjToO3n/5UOMu2BElqwG4WO9ctmT4NYgjg4yGFE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--namangulati.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=utlUI72m; arc=none smtp.client-ip=209.85.222.200 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--namangulati.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="utlUI72m" Received: by mail-qk1-f200.google.com with SMTP id af79cd13be357-939f27c80a3so223877085a.1 for ; Fri, 11 Sep 2026 18:11:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1789175479; x=1789780279; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:mime-version:date:from :to:cc:subject:date:message-id:reply-to:content-type; bh=Tj1falKDmwZv4EHgKITMnazbfSQ8aahAK4wcOUV9Ux4=; b=utlUI72mFHnxKAoepbO1dq9abyciRINtThNYU8EziifnOfEiDNcthZtfRZ2S3/O0/D Pa8nQitp2keQvMFQg2rmQF/i7Xx9YnG6h6OGpN8uQT7huNZANuudAvQtoADecvB1NWgE gYA9l15/7Ps/6D2ceWsIi/29d+PlSpR/4lFJ6nv2MPlM3rUuKg4o+HhotWCmI1vPilZV rNBSbDytJn5chstG44+wdQiitzQoZmsC6xvO5F3SdNQMMuLt181rhqySdSCTOrk+UL5u D68MXRK6hOSpdn+eXuxKsBi/6kU8a03VgGf/hD4ypA0iU8sgLz2IKs3YHsLGAHKOoXSQ 7XoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1789175479; x=1789780279; h=content-type:cc:to:from:subject:message-id:mime-version:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=Tj1falKDmwZv4EHgKITMnazbfSQ8aahAK4wcOUV9Ux4=; b=JtfyveBPe2jbgEoBizTAB9RSyTzJWEZvN/pSVb6KbH7MTfeVpk2P0p8LCvR1DVuZQj nVpf0aAlaILy5FabmHDacch4nNHq3iqrpUCYwEX9I1HEtZ7wjn2tYqOoU1P26QLcFSwn ZgxWNhqQBSWkURlbgc0soxPZY3+49tb02umRJJ2O5oTvQuF2za7xkMl5ZWAp7GcSwBmQ oj4aVvEjXQSaHQg0f1M0CzrGpHs9jxabpIVA5YdG4PzhXamKqRg3HRFStVnT2nwPiWtq +65nWHlPEdXKSCN4cohutYg2ZJAG6IdY7AUw0JJRG8eptbAAYH+dElw7anGiT61GjUwO ScEg== X-Forwarded-Encrypted: i=1; AKwUvBw9pmaXnJZB5lsnCqoHd7dw/3aICWAfiHU9JRey+QxN8XaYAvj3YanJ1f6XHEGRZcvnExaD46A=@vger.kernel.org X-Gm-Message-State: AFuF++mIEIVkrQWInvonH+oJQIzeXmmqbndsy4GYtoXkXyR2e8iffRSE GJX0ucIgNacAs6nQt9TZDzJpjRnQKE2cGHX6kKft22OzhNYLstRFG7IBZg3q/5327Rxlr7euc6m i9TaCsYg/pEIkLX/pQueSnQUMnQ== X-Received: from qkbe26-n2.prod.google.com ([2002:a05:620a:a41a:20b0:93a:761:e75c]) (user=namangulati job=prod-delivery.src-stubby-dispatcher) by 2002:a05:620a:4443:b0:936:eeab:307e with SMTP id af79cd13be357-93a0357e40fmr130193285a.9.1789175478663; Fri, 11 Sep 2026 18:11:18 -0700 (PDT) Date: Sat, 12 Sep 2026 01:10:51 +0000 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.1007.g17ff1f9808-goog Message-ID: <20260912011051.4092897-1-namangulati@google.com> Subject: [PATCH net] netfilter: ctnetlink: fix suspicious RCU usage in expect_iter_name From: Naman Gulati To: Pablo Neira Ayuso , Florian Westphal , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Phil Sutter , Simon Horman , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, syzbot+4bd730aede2791e40bdf@syzkaller.appspotmail.com, Naman Gulati Content-Type: text/plain; charset="UTF-8" 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 --- 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 579ada063b1b..4e5d7c701436 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -3392,7 +3392,8 @@ 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; -- 2.55.0.1007.g17ff1f9808-goog