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 83FD43FCB3D; Wed, 30 Sep 2026 19:31:35 +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=1790796696; cv=none; b=WQKWr5qbWzoN/eGUknU0y2fWiyomgH0GmQAN9kg3wWtnp02dmtS3k7gaXNgpsa5EP+dNzoVvuSDs/fJLAV8HIPdjZU/v/5Sxq/rhghvNpxj2wZbKvXNIAtoU+XE5aSBMhXtZg/vLiEZwgCssvTWLzMbuqaSu6Gv0h8A3iRVAkGY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790796696; c=relaxed/simple; bh=/JBfn4cKpNJlnXBxPMcU2HAgy2dyXKdTF/zmoxGJWzs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ln2SdAAh9booHLHj4lbzAx3di8n0mzfE0d414u/MzmQpLxZfho0p/Qyd3jHKraUJSxvojH/ETuKpBOcMajQF+jhR/+Zpk/2k2BbS4LMc0I5G0KiPKyyR6ikDD2Y12q7KnqfVNHbh+9isxONf4N/QC4elSyZd8leOiKLZOKRxiuA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=teLYn63C; 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="teLYn63C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E240F1F000FF; Wed, 30 Sep 2026 19:31:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790796695; bh=uwHdKmbdddI82yIQuHFKcXcQcTU4i4+mTZj9DHf7oNw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=teLYn63Car/iesRoFspVlkFAHrcNNMFMiLXmxTAffkNK6fdgqP1kckVlGp1sJ5PXp 61NTFtw5tz8u1ROIi7pPO6WDQzEj3Oh5Tdw2UFlbnqEI2Ca2vHtfSjsxf/NhyBJt6K QidSF5CfGZJWDe0iRbG547Y9gvwUo2qufll4iF6s= 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 6.6 0997/1193] netfilter: ctnetlink: fix suspicious RCU usage in expect_iter_name Date: Wed, 30 Sep 2026 17:28:01 +0200 Message-ID: <20260930152456.390729525@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@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: 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 979d3e71407eb..537a44967bc8b 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -3384,7 +3384,8 @@ 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