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 72F89C7EE37 for ; Tue, 6 Jun 2023 22:59:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240135AbjFFW7H (ORCPT ); Tue, 6 Jun 2023 18:59:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44468 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240148AbjFFW7D (ORCPT ); Tue, 6 Jun 2023 18:59:03 -0400 Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 362BE1739; Tue, 6 Jun 2023 15:58:59 -0700 (PDT) From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, fw@strlen.de Subject: [PATCH net 3/5] netfilter: conntrack: fix NULL pointer dereference in nf_confirm_cthelper Date: Wed, 7 Jun 2023 00:58:49 +0200 Message-Id: <20230606225851.67394-4-pablo@netfilter.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230606225851.67394-1-pablo@netfilter.org> References: <20230606225851.67394-1-pablo@netfilter.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org From: Tijs Van Buggenhout 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 --- 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 c4ccfec6cb98..d119f1d4c2fc 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -2260,6 +2260,9 @@ 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; -- 2.30.2