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 X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31110C2F3BE for ; Mon, 21 Jan 2019 14:00:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 013492087F for ; Mon, 21 Jan 2019 14:00:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548079205; bh=8X89epfTPxoZttnMGavahmKESlm/LzEPaYStJRevPvc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jTssjS0mcIkMFThd2v0MbVZ8pCRzXfF2Juy5pTdrCMDVuFaFfmoYm2/Q4ZkzYnaxf tX7+r0tSIwojz5oDtbR/NL0cpNCiZXvl4mnFtpgU3xKT0d7i38S8YzFga7m1tIjiYU +6aHmO5kH91FRFV8pla6VsVPHb891MyDBceBtZgk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732304AbfAUOAD (ORCPT ); Mon, 21 Jan 2019 09:00:03 -0500 Received: from mail.kernel.org ([198.145.29.99]:46266 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732293AbfAUOAA (ORCPT ); Mon, 21 Jan 2019 09:00:00 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B8E6B2087F; Mon, 21 Jan 2019 13:59:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548079199; bh=8X89epfTPxoZttnMGavahmKESlm/LzEPaYStJRevPvc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EDDN8wvUXy4sgvomb4LE+cx5h4kNu5Hru7DZ5+163ORjuR0XQUG0z4ys8XJ0GYnJM tcmH7E7731BK6ydfFe72TkUzFl4jz6T0ESuD2k7kd22HjwXa7fG4nPu7M93m4syXjO wwwTWrbTlm4pihu7sK+uNzG9x9rXIfZFqVGZGie4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Shawn Bohrer , Florian Westphal , Pablo Neira Ayuso Subject: [PATCH 4.19 08/99] netfilter: nf_conncount: split gc in two phases Date: Mon, 21 Jan 2019 14:48:00 +0100 Message-Id: <20190121134914.234510860@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190121134913.924726465@linuxfoundation.org> References: <20190121134913.924726465@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Florian Westphal commit f7fcc98dfc2d136722007fec0debbed761679b94 upstream. The lockless workqueue garbage collector can race with packet path garbage collector to delete list nodes, as it calls tree_nodes_free() with the addresses of nodes that might have been free'd already from another cpu. To fix this, split gc into two phases. One phase to perform gc on the connections: From a locking perspective, this is the same as count_tree(): we hold rcu lock, but we do not change the tree, we only change the nodes' contents. The second phase acquires the tree lock and reaps empty nodes. This avoids a race condition of the garbage collection vs. packet path: If a node has been free'd already, the second phase won't find it anymore. This second phase is, from locking perspective, same as insert_tree(). The former only modifies nodes (list content, count), latter modifies the tree itself (rb_erase or rb_insert). Fixes: 5c789e131cbb9 ("netfilter: nf_conncount: Add list lock and gc worker, and RCU for init tree search") Reviewed-by: Shawn Bohrer Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- net/netfilter/nf_conncount.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) --- a/net/netfilter/nf_conncount.c +++ b/net/netfilter/nf_conncount.c @@ -500,16 +500,32 @@ static void tree_gc_worker(struct work_s for (node = rb_first(root); node != NULL; node = rb_next(node)) { rbconn = rb_entry(node, struct nf_conncount_rb, node); if (nf_conncount_gc_list(data->net, &rbconn->list)) - gc_nodes[gc_count++] = rbconn; + gc_count++; } rcu_read_unlock(); spin_lock_bh(&nf_conncount_locks[tree]); + if (gc_count < ARRAY_SIZE(gc_nodes)) + goto next; /* do not bother */ - if (gc_count) { - tree_nodes_free(root, gc_nodes, gc_count); + gc_count = 0; + node = rb_first(root); + while (node != NULL) { + rbconn = rb_entry(node, struct nf_conncount_rb, node); + node = rb_next(node); + + if (rbconn->list.count > 0) + continue; + + gc_nodes[gc_count++] = rbconn; + if (gc_count >= ARRAY_SIZE(gc_nodes)) { + tree_nodes_free(root, gc_nodes, gc_count); + gc_count = 0; + } } + tree_nodes_free(root, gc_nodes, gc_count); +next: clear_bit(tree, data->pending_trees); next_tree = (tree + 1) % CONNCOUNT_SLOTS;