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 57B8FC6FA99 for ; Fri, 10 Mar 2023 14:08:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231741AbjCJOH7 (ORCPT ); Fri, 10 Mar 2023 09:07:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33674 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231656AbjCJOHl (ORCPT ); Fri, 10 Mar 2023 09:07:41 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64B8B11758B for ; Fri, 10 Mar 2023 06:07:06 -0800 (PST) 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 1337D618A6 for ; Fri, 10 Mar 2023 14:07:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06F64C4339B; Fri, 10 Mar 2023 14:07:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678457223; bh=v39AbY21yJH2RbjjHHoqHB0sqEV9P+UMlIe3bHbqTY8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YcUiTTDKTVaTvcmK2Y4w46CMkBn4Khv+jLHX6VnHt3wrXp1L8SmFAs/glRwCi1f+F m5fk5QMt83XT5EDurH1x1chtfaQQasrU9nd+IPaG1a0ji5hD2UdePfYU20wY6w289G bvT2L0SFweGWQ5A6csayS4kC1RKOfwPl34sCgiHg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Florian Westphal , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH 6.1 061/200] netfilter: conntrack: fix rmmod double-free race Date: Fri, 10 Mar 2023 14:37:48 +0100 Message-Id: <20230310133719.002715458@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133717.050159289@linuxfoundation.org> References: <20230310133717.050159289@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: Florian Westphal [ Upstream commit e6d57e9ff0aec323717ee36fc9ea34ad89217151 ] nf_conntrack_hash_check_insert() callers free the ct entry directly, via nf_conntrack_free. This isn't safe anymore because nf_conntrack_hash_check_insert() might place the entry into the conntrack table and then delteted the entry again because it found that a conntrack extension has been removed at the same time. In this case, the just-added entry is removed again and an error is returned to the caller. Problem is that another cpu might have picked up this entry and incremented its reference count. This results in a use-after-free/double-free, once by the other cpu and once by the caller of nf_conntrack_hash_check_insert(). Fix this by making nf_conntrack_hash_check_insert() not fail anymore after the insertion, just like before the 'Fixes' commit. This is safe because a racing nf_ct_iterate() has to wait for us to release the conntrack hash spinlocks. While at it, make the function return -EAGAIN in the rmmod (genid changed) case, this makes nfnetlink replay the command (suggested by Pablo Neira). Fixes: c56716c69ce1 ("netfilter: extensions: introduce extension genid count") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_conntrack_bpf.c | 1 - net/netfilter/nf_conntrack_core.c | 25 +++++++++++++++---------- net/netfilter/nf_conntrack_netlink.c | 3 --- 3 files changed, 15 insertions(+), 14 deletions(-) diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c index 8639e7efd0e22..adae86e8e02e8 100644 --- a/net/netfilter/nf_conntrack_bpf.c +++ b/net/netfilter/nf_conntrack_bpf.c @@ -384,7 +384,6 @@ struct nf_conn *bpf_ct_insert_entry(struct nf_conn___init *nfct_i) struct nf_conn *nfct = (struct nf_conn *)nfct_i; int err; - nfct->status |= IPS_CONFIRMED; err = nf_conntrack_hash_check_insert(nfct); if (err < 0) { nf_conntrack_free(nfct); diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 23b3fedd619a5..7f0f3bcaae031 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -890,10 +890,8 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) zone = nf_ct_zone(ct); - if (!nf_ct_ext_valid_pre(ct->ext)) { - NF_CT_STAT_INC_ATOMIC(net, insert_failed); - return -ETIMEDOUT; - } + if (!nf_ct_ext_valid_pre(ct->ext)) + return -EAGAIN; local_bh_disable(); do { @@ -928,6 +926,19 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) goto chaintoolong; } + /* If genid has changed, we can't insert anymore because ct + * extensions could have stale pointers and nf_ct_iterate_destroy + * might have completed its table scan already. + * + * Increment of the ext genid right after this check is fine: + * nf_ct_iterate_destroy blocks until locks are released. + */ + if (!nf_ct_ext_valid_post(ct->ext)) { + err = -EAGAIN; + goto out; + } + + ct->status |= IPS_CONFIRMED; smp_wmb(); /* The caller holds a reference to this object */ refcount_set(&ct->ct_general.use, 2); @@ -936,12 +947,6 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) NF_CT_STAT_INC(net, insert); local_bh_enable(); - if (!nf_ct_ext_valid_post(ct->ext)) { - nf_ct_kill(ct); - NF_CT_STAT_INC_ATOMIC(net, drop); - return -ETIMEDOUT; - } - return 0; chaintoolong: NF_CT_STAT_INC(net, chaintoolong); diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index ca4d5bb1ea524..733bb56950c14 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -2316,9 +2316,6 @@ ctnetlink_create_conntrack(struct net *net, nfct_seqadj_ext_add(ct); nfct_synproxy_ext_add(ct); - /* we must add conntrack extensions before confirmation. */ - ct->status |= IPS_CONFIRMED; - if (cda[CTA_STATUS]) { err = ctnetlink_change_status(ct, cda); if (err < 0) -- 2.39.2