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 5408451A14B; Wed, 30 Sep 2026 17:25:30 +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=1790789131; cv=none; b=IbtYB4Fn2bR7Uwr7QfSLqCVu1TlkCoz6NwqhnNTN7dEgUAQsekSzGT+Zf8YsxYO7NeFHSoTlZllytWLKDqaD3OvgSgj1+Ltx1hptTV7n4xCMkKOPAW5AArffFpYECGBU7psRF5e2g7JK0MKvk/JQJrwxcmNfk9N0aL46mxtnIuw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790789131; c=relaxed/simple; bh=KdbkWLhWGlBxymb6BTF/VWlooJBnaxSbd4uuwdfD4Co=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IKRGh2+p68uqgRzxNxrX/VupOx6poG0c6ymkhVtUca+Lc2EWBpUIf7eB/1IXxam3ef7ibVjvw8mMgbj4nCbj89d1wzF35SS870Husq7grO5nAjt2er9edj9bTbvBu5ToAG0pKJOTgHJsqskwiNrCnHdt73TK7+sJpQFkJbURZQw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pn/YEnXh; 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="pn/YEnXh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A870F1F000FF; Wed, 30 Sep 2026 17:25:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790789130; bh=G/JPodqhpihMVIOE0rUqPoHq4Pcm8S4qgK25CgoXgTo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=pn/YEnXhH3EmtTgwpLnMr7piJj2ZctV3rWQHHWz6ZZJvhps0esVXusLPI0pSb4MCj PcXzyb7M3Z1AgZ4U91UUx9JIuqo2rqefEsWX/R057ypTrdbrOiZ2+TjYiF6FOK3++O fM9IUf4OWG6ebtaFP5R9TfGD69BkPDe/oDUq0TGM= 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 6.12 352/877] netfilter: ctnetlink: fix suspicious RCU usage in expect_iter_name Date: Wed, 30 Sep 2026 17:21:03 +0200 Message-ID: <20260930152422.268512725@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152414.738996857@linuxfoundation.org> References: <20260930152414.738996857@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 6.12-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 a081d38702f5d..8bb32965edb83 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -3390,7 +3390,8 @@ 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