net: openvswitch: ovs_ct_exit to be done under ovs_lock

syzbot wrote:
| =============================
| WARNING: suspicious RCU usage
| 5.7.0-rc1+ #45 Not tainted
| -----------------------------
| net/openvswitch/conntrack.c:1898 RCU-list traversed in non-reader section!!
|
| other info that might help us debug this:
| rcu_scheduler_active = 2, debug_locks = 1
| ...
|
| stack backtrace:
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
| Workqueue: netns cleanup_net
| Call Trace:
| ...
| ovs_ct_exit
| ovs_exit_net
| ops_exit_list.isra.7
| cleanup_net
| process_one_work
| worker_thread

To avoid that warning, invoke the ovs_ct_exit under ovs_lock and add
lockdep_ovsl_is_held as optional lockdep expression.

Link: https://lore.kernel.org/lkml/000000000000e642a905a0cbee6e@google.com
Fixes: 11efd5cb04a1 ("openvswitch: Support conntrack zone limit")
Cc: Pravin B Shelar <pshelar@ovn.org>
Cc: Yi-Hung Wei <yihung.wei@gmail.com>
Reported-by: syzbot+7ef50afd3a211f879112@syzkaller.appspotmail.com
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index e726159..4340f25 100644 (file)
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -1895,7 +1895,8 @@ static void ovs_ct_limit_exit(struct net *net, struct ovs_net *ovs_net)
                struct hlist_head *head = &info->limits[i];
                struct ovs_ct_limit *ct_limit;
 
-               hlist_for_each_entry_rcu(ct_limit, head, hlist_node)
+               hlist_for_each_entry_rcu(ct_limit, head, hlist_node,
+                                        lockdep_ovsl_is_held())
                        kfree_rcu(ct_limit, rcu);
        }
        kfree(ovs_net->ct_limit_info->limits);

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index d8ae541..94b0245 100644 (file)
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -2466,8 +2466,10 @@ static void __net_exit ovs_exit_net(struct net *dnet)
        struct net *net;
        LIST_HEAD(head);
 
-       ovs_ct_exit(dnet);
        ovs_lock();
+
+       ovs_ct_exit(dnet);
+
        list_for_each_entry_safe(dp, dp_next, &ovs_net->dps, list_node)
                __dp_destroy(dp);