From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70FFAC7EE25 for ; Mon, 12 Jun 2023 10:46:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229699AbjFLKqT (ORCPT ); Mon, 12 Jun 2023 06:46:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52252 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231811AbjFLKqD (ORCPT ); Mon, 12 Jun 2023 06:46:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EFA8FF7FE for ; Mon, 12 Jun 2023 03:30:39 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 87C6561500 for ; Mon, 12 Jun 2023 10:30:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D422C433EF; Mon, 12 Jun 2023 10:30:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1686565839; bh=nLrUB/ipY9U+VtnRqHyd7BJmuuE8q4WPua2Cow98l7U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ybbONk1j5uaTTWUnQ03/+g6sgbJgSVjbyceSGxL0HVwxiTOpzycbJ7KiRanpUaN6y /LWStt1ONoP8bBKPmgNBdfLYb+1UP/I6cC8CkpbxTV4Rk86mqSGJZt5LjPLeSuj+re L7r+AWWVkjAExH6DcOhUr08al5Kozq/gYJPgvGQ8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tijs Van Buggenhout , Florian Westphal , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 5.4 11/45] netfilter: conntrack: fix NULL pointer dereference in nf_confirm_cthelper Date: Mon, 12 Jun 2023 12:26:05 +0200 Message-ID: <20230612101655.083150941@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230612101654.644983109@linuxfoundation.org> References: <20230612101654.644983109@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Tijs Van Buggenhout [ Upstream commit e1f543dc660b44618a1bd72ddb4ca0828a95f7ad ] An nf_conntrack_helper from nf_conn_help may become NULL after DNAT. Observed when TCP port 1720 (Q931_PORT), associated with h323 conntrack helper, is DNAT'ed to another destination port (e.g. 1730), while nfqueue is being used for final acceptance (e.g. snort). This happenned after transition from kernel 4.14 to 5.10.161. Workarounds: * keep the same port (1720) in DNAT * disable nfqueue * disable/unload h323 NAT helper $ linux-5.10/scripts/decode_stacktrace.sh vmlinux < /tmp/kernel.log BUG: kernel NULL pointer dereference, address: 0000000000000084 [..] RIP: 0010:nf_conntrack_update (net/netfilter/nf_conntrack_core.c:2080 net/netfilter/nf_conntrack_core.c:2134) nf_conntrack [..] nfqnl_reinject (net/netfilter/nfnetlink_queue.c:237) nfnetlink_queue nfqnl_recv_verdict (net/netfilter/nfnetlink_queue.c:1230) nfnetlink_queue nfnetlink_rcv_msg (net/netfilter/nfnetlink.c:241) nfnetlink [..] Fixes: ee04805ff54a ("netfilter: conntrack: make conntrack userspace helpers work again") Signed-off-by: Tijs Van Buggenhout Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_conntrack_core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index d9b6f2001d006..fb1f12bb0ff2c 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1943,6 +1943,9 @@ static int nf_confirm_cthelper(struct sk_buff *skb, struct nf_conn *ct, return 0; helper = rcu_dereference(help->helper); + if (!helper) + return 0; + if (!(helper->flags & NF_CT_HELPER_F_USERSPACE)) return 0; -- 2.39.2