From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 568F9171A1 for ; Mon, 22 May 2023 19:22:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C7C41C433EF; Mon, 22 May 2023 19:22:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684783342; bh=QBvUyuGFnxd8+jSmOjULfKCgTTdHZtR048u9lD6AjcM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mz43zQFa76Nx++HivwwO4/0RlOhDvd1ju5O7j4fQYgzISbKE+ZIb8+8sivPDZn5+K P18PYU7+wzSpp2dgSgUkDGTRVL6Oli7NBlz2pF7lEzFN4tgO4Y9LTtz+en+N9rvSW3 XkPanX5ZtlIL2y1LOtj00P2aD7hWvd15It3hzJkg= 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 6.1 013/292] netfilter: conntrack: fix possible bug_on with enable_hooks=1 Date: Mon, 22 May 2023 20:06:10 +0100 Message-Id: <20230522190406.223046923@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230522190405.880733338@linuxfoundation.org> References: <20230522190405.880733338@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Florian Westphal [ Upstream commit e72eeab542dbf4f544e389e64fa13b82a1b6d003 ] I received a bug report (no reproducer so far) where we trip over 712 rcu_read_lock(); 713 ct_hook = rcu_dereference(nf_ct_hook); 714 BUG_ON(ct_hook == NULL); // here In nf_conntrack_destroy(). First turn this BUG_ON into a WARN. I think it was triggered via enable_hooks=1 flag. When this flag is turned on, the conntrack hooks are registered before nf_ct_hook pointer gets assigned. This opens a short window where packets enter the conntrack machinery, can have skb->_nfct set up and a subsequent kfree_skb might occur before nf_ct_hook is set. Call nf_conntrack_init_end() to set nf_ct_hook before we register the pernet ops. Fixes: ba3fbe663635 ("netfilter: nf_conntrack: provide modparam to always register conntrack hooks") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/core.c | 6 ++++-- net/netfilter/nf_conntrack_standalone.c | 3 ++- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/net/netfilter/core.c b/net/netfilter/core.c index 6e80f0f6149ea..55a7f72d547cd 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -699,9 +699,11 @@ void nf_conntrack_destroy(struct nf_conntrack *nfct) rcu_read_lock(); ct_hook = rcu_dereference(nf_ct_hook); - BUG_ON(ct_hook == NULL); - ct_hook->destroy(nfct); + if (ct_hook) + ct_hook->destroy(nfct); rcu_read_unlock(); + + WARN_ON(!ct_hook); } EXPORT_SYMBOL(nf_conntrack_destroy); diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c index 460294bd4b606..52245dbfae311 100644 --- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -1222,11 +1222,12 @@ static int __init nf_conntrack_standalone_init(void) nf_conntrack_htable_size_user = nf_conntrack_htable_size; #endif + nf_conntrack_init_end(); + ret = register_pernet_subsys(&nf_conntrack_net_ops); if (ret < 0) goto out_pernet; - nf_conntrack_init_end(); return 0; out_pernet: -- 2.39.2