Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937208AbdCJNUw (ORCPT ); Fri, 10 Mar 2017 08:20:52 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43726 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933101AbdCJLwl (ORCPT ); Fri, 10 Mar 2017 06:52:41 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Andrew Collins" Date: Fri, 10 Mar 2017 11:46:23 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 329/370] net: Add netdev all_adj_list refcnt propagation to fix panic In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9038 Lines: 269 3.16.42-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Andrew Collins [ Upstream commit 93409033ae653f1c9a949202fb537ab095b2092f ] This is a respin of a patch to fix a relatively easily reproducible kernel panic related to the all_adj_list handling for netdevs in recent kernels. The following sequence of commands will reproduce the issue: ip link add link eth0 name eth0.100 type vlan id 100 ip link add link eth0 name eth0.200 type vlan id 200 ip link add name testbr type bridge ip link set eth0.100 master testbr ip link set eth0.200 master testbr ip link add link testbr mac0 type macvlan ip link delete dev testbr This creates an upper/lower tree of (excuse the poor ASCII art): /---eth0.100-eth0 mac0-testbr- \---eth0.200-eth0 When testbr is deleted, the all_adj_lists are walked, and eth0 is deleted twice from the mac0 list. Unfortunately, during setup in __netdev_upper_dev_link, only one reference to eth0 is added, so this results in a panic. This change adds reference count propagation so things are handled properly. Matthias Schiffer reported a similar crash in batman-adv: https://github.com/freifunk-gluon/gluon/issues/680 https://www.open-mesh.org/issues/247 which this patch also seems to resolve. Signed-off-by: Andrew Collins Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/core/dev.c | 68 ++++++++++++++++++++++++++++++++-------------------------- 1 file changed, 37 insertions(+), 31 deletions(-) --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4812,6 +4812,7 @@ static inline bool netdev_adjacent_is_ne static int __netdev_adjacent_dev_insert(struct net_device *dev, struct net_device *adj_dev, + u16 ref_nr, struct list_head *dev_list, void *private, bool master) { @@ -4821,7 +4822,7 @@ static int __netdev_adjacent_dev_insert( adj = __netdev_find_adj(dev, adj_dev, dev_list); if (adj) { - adj->ref_nr++; + adj->ref_nr += ref_nr; return 0; } @@ -4831,7 +4832,7 @@ static int __netdev_adjacent_dev_insert( adj->dev = adj_dev; adj->master = master; - adj->ref_nr = 1; + adj->ref_nr = ref_nr; adj->private = private; dev_hold(adj_dev); @@ -4870,6 +4871,7 @@ free_adj: static void __netdev_adjacent_dev_remove(struct net_device *dev, struct net_device *adj_dev, + u16 ref_nr, struct list_head *dev_list) { struct netdev_adjacent *adj; @@ -4882,10 +4884,10 @@ static void __netdev_adjacent_dev_remove BUG(); } - if (adj->ref_nr > 1) { - pr_debug("%s to %s ref_nr-- = %d\n", dev->name, adj_dev->name, - adj->ref_nr-1); - adj->ref_nr--; + if (adj->ref_nr > ref_nr) { + pr_debug("%s to %s ref_nr-%d = %d\n", dev->name, adj_dev->name, + ref_nr, adj->ref_nr-ref_nr); + adj->ref_nr -= ref_nr; return; } @@ -4904,21 +4906,22 @@ static void __netdev_adjacent_dev_remove static int __netdev_adjacent_dev_link_lists(struct net_device *dev, struct net_device *upper_dev, + u16 ref_nr, struct list_head *up_list, struct list_head *down_list, void *private, bool master) { int ret; - ret = __netdev_adjacent_dev_insert(dev, upper_dev, up_list, private, - master); + ret = __netdev_adjacent_dev_insert(dev, upper_dev, ref_nr, up_list, + private, master); if (ret) return ret; - ret = __netdev_adjacent_dev_insert(upper_dev, dev, down_list, private, - false); + ret = __netdev_adjacent_dev_insert(upper_dev, dev, ref_nr, down_list, + private, false); if (ret) { - __netdev_adjacent_dev_remove(dev, upper_dev, up_list); + __netdev_adjacent_dev_remove(dev, upper_dev, ref_nr, up_list); return ret; } @@ -4926,9 +4929,10 @@ static int __netdev_adjacent_dev_link_li } static int __netdev_adjacent_dev_link(struct net_device *dev, - struct net_device *upper_dev) + struct net_device *upper_dev, + u16 ref_nr) { - return __netdev_adjacent_dev_link_lists(dev, upper_dev, + return __netdev_adjacent_dev_link_lists(dev, upper_dev, ref_nr, &dev->all_adj_list.upper, &upper_dev->all_adj_list.lower, NULL, false); @@ -4936,17 +4940,19 @@ static int __netdev_adjacent_dev_link(st static void __netdev_adjacent_dev_unlink_lists(struct net_device *dev, struct net_device *upper_dev, + u16 ref_nr, struct list_head *up_list, struct list_head *down_list) { - __netdev_adjacent_dev_remove(dev, upper_dev, up_list); - __netdev_adjacent_dev_remove(upper_dev, dev, down_list); + __netdev_adjacent_dev_remove(dev, upper_dev, ref_nr, up_list); + __netdev_adjacent_dev_remove(upper_dev, dev, ref_nr, down_list); } static void __netdev_adjacent_dev_unlink(struct net_device *dev, - struct net_device *upper_dev) + struct net_device *upper_dev, + u16 ref_nr) { - __netdev_adjacent_dev_unlink_lists(dev, upper_dev, + __netdev_adjacent_dev_unlink_lists(dev, upper_dev, ref_nr, &dev->all_adj_list.upper, &upper_dev->all_adj_list.lower); } @@ -4955,17 +4961,17 @@ static int __netdev_adjacent_dev_link_ne struct net_device *upper_dev, void *private, bool master) { - int ret = __netdev_adjacent_dev_link(dev, upper_dev); + int ret = __netdev_adjacent_dev_link(dev, upper_dev, 1); if (ret) return ret; - ret = __netdev_adjacent_dev_link_lists(dev, upper_dev, + ret = __netdev_adjacent_dev_link_lists(dev, upper_dev, 1, &dev->adj_list.upper, &upper_dev->adj_list.lower, private, master); if (ret) { - __netdev_adjacent_dev_unlink(dev, upper_dev); + __netdev_adjacent_dev_unlink(dev, upper_dev, 1); return ret; } @@ -4975,8 +4981,8 @@ static int __netdev_adjacent_dev_link_ne static void __netdev_adjacent_dev_unlink_neighbour(struct net_device *dev, struct net_device *upper_dev) { - __netdev_adjacent_dev_unlink(dev, upper_dev); - __netdev_adjacent_dev_unlink_lists(dev, upper_dev, + __netdev_adjacent_dev_unlink(dev, upper_dev, 1); + __netdev_adjacent_dev_unlink_lists(dev, upper_dev, 1, &dev->adj_list.upper, &upper_dev->adj_list.lower); } @@ -5017,7 +5023,7 @@ static int __netdev_upper_dev_link(struc list_for_each_entry(j, &upper_dev->all_adj_list.upper, list) { pr_debug("Interlinking %s with %s, non-neighbour\n", i->dev->name, j->dev->name); - ret = __netdev_adjacent_dev_link(i->dev, j->dev); + ret = __netdev_adjacent_dev_link(i->dev, j->dev, i->ref_nr); if (ret) goto rollback_mesh; } @@ -5027,7 +5033,7 @@ static int __netdev_upper_dev_link(struc list_for_each_entry(i, &upper_dev->all_adj_list.upper, list) { pr_debug("linking %s's upper device %s with %s\n", upper_dev->name, i->dev->name, dev->name); - ret = __netdev_adjacent_dev_link(dev, i->dev); + ret = __netdev_adjacent_dev_link(dev, i->dev, i->ref_nr); if (ret) goto rollback_upper_mesh; } @@ -5036,7 +5042,7 @@ static int __netdev_upper_dev_link(struc list_for_each_entry(i, &dev->all_adj_list.lower, list) { pr_debug("linking %s's lower device %s with %s\n", dev->name, i->dev->name, upper_dev->name); - ret = __netdev_adjacent_dev_link(i->dev, upper_dev); + ret = __netdev_adjacent_dev_link(i->dev, upper_dev, i->ref_nr); if (ret) goto rollback_lower_mesh; } @@ -5049,7 +5055,7 @@ rollback_lower_mesh: list_for_each_entry(i, &dev->all_adj_list.lower, list) { if (i == to_i) break; - __netdev_adjacent_dev_unlink(i->dev, upper_dev); + __netdev_adjacent_dev_unlink(i->dev, upper_dev, i->ref_nr); } i = NULL; @@ -5059,7 +5065,7 @@ rollback_upper_mesh: list_for_each_entry(i, &upper_dev->all_adj_list.upper, list) { if (i == to_i) break; - __netdev_adjacent_dev_unlink(dev, i->dev); + __netdev_adjacent_dev_unlink(dev, i->dev, i->ref_nr); } i = j = NULL; @@ -5071,7 +5077,7 @@ rollback_mesh: list_for_each_entry(j, &upper_dev->all_adj_list.upper, list) { if (i == to_i && j == to_j) break; - __netdev_adjacent_dev_unlink(i->dev, j->dev); + __netdev_adjacent_dev_unlink(i->dev, j->dev, i->ref_nr); } if (i == to_i) break; @@ -5147,16 +5153,16 @@ void netdev_upper_dev_unlink(struct net_ */ list_for_each_entry(i, &dev->all_adj_list.lower, list) list_for_each_entry(j, &upper_dev->all_adj_list.upper, list) - __netdev_adjacent_dev_unlink(i->dev, j->dev); + __netdev_adjacent_dev_unlink(i->dev, j->dev, i->ref_nr); /* remove also the devices itself from lower/upper device * list */ list_for_each_entry(i, &dev->all_adj_list.lower, list) - __netdev_adjacent_dev_unlink(i->dev, upper_dev); + __netdev_adjacent_dev_unlink(i->dev, upper_dev, i->ref_nr); list_for_each_entry(i, &upper_dev->all_adj_list.upper, list) - __netdev_adjacent_dev_unlink(dev, i->dev); + __netdev_adjacent_dev_unlink(dev, i->dev, i->ref_nr); call_netdevice_notifiers(NETDEV_CHANGEUPPER, dev); }