Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:42160 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933245AbeBWSnQ (ORCPT ); Fri, 23 Feb 2018 13:43:16 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , Sowmini Varadhan , Santosh Shilimkar , "David S. Miller" Subject: [PATCH 4.9 028/145] rds: tcp: atomically purge entries from rds_tcp_conn_list during netns delete Date: Fri, 23 Feb 2018 19:25:34 +0100 Message-Id: <20180223170728.477640744@linuxfoundation.org> In-Reply-To: <20180223170724.669759283@linuxfoundation.org> References: <20180223170724.669759283@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sowmini Varadhan commit f10b4cff98c6977668434fbf5dd58695eeca2897 upstream. The rds_tcp_kill_sock() function parses the rds_tcp_conn_list to find the rds_connection entries marked for deletion as part of the netns deletion under the protection of the rds_tcp_conn_lock. Since the rds_tcp_conn_list tracks rds_tcp_connections (which have a 1:1 mapping with rds_conn_path), multiple tc entries in the rds_tcp_conn_list will map to a single rds_connection, and will be deleted as part of the rds_conn_destroy() operation that is done outside the rds_tcp_conn_lock. The rds_tcp_conn_list traversal done under the protection of rds_tcp_conn_lock should not leave any doomed tc entries in the list after the rds_tcp_conn_lock is released, else another concurrently executiong netns delete (for a differnt netns) thread may trip on these entries. Reported-by: syzbot Signed-off-by: Sowmini Varadhan Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/rds/tcp.c | 9 +++++++-- net/rds/tcp.h | 1 + 2 files changed, 8 insertions(+), 2 deletions(-) --- a/net/rds/tcp.c +++ b/net/rds/tcp.c @@ -303,7 +303,8 @@ static void rds_tcp_conn_free(void *arg) rdsdebug("freeing tc %p\n", tc); spin_lock_irqsave(&rds_tcp_conn_lock, flags); - list_del(&tc->t_tcp_node); + if (!tc->t_tcp_node_detached) + list_del(&tc->t_tcp_node); spin_unlock_irqrestore(&rds_tcp_conn_lock, flags); kmem_cache_free(rds_tcp_conn_slab, tc); @@ -528,8 +529,12 @@ static void rds_tcp_kill_sock(struct net if (net != c_net || !tc->t_sock) continue; - if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn)) + if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn)) { list_move_tail(&tc->t_tcp_node, &tmp_list); + } else { + list_del(&tc->t_tcp_node); + tc->t_tcp_node_detached = true; + } } spin_unlock_irq(&rds_tcp_conn_lock); list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) { --- a/net/rds/tcp.h +++ b/net/rds/tcp.h @@ -11,6 +11,7 @@ struct rds_tcp_incoming { struct rds_tcp_connection { struct list_head t_tcp_node; + bool t_tcp_node_detached; struct rds_conn_path *t_cpath; /* t_conn_path_lock synchronizes the connection establishment between * rds_tcp_accept_one and rds_tcp_conn_path_connect