Patch "net: openvswitch: ovs_ct_exit to be done under ovs_lock" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: openvswitch: ovs_ct_exit to be done under ovs_lock

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-openvswitch-ovs_ct_exit-to-be-done-under-ovs_loc.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d910ac79e9895b7ee2628ac4269935ebe68ccd21
Author: Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx>
Date:   Fri Apr 17 02:57:31 2020 +0800

    net: openvswitch: ovs_ct_exit to be done under ovs_lock
    
    [ Upstream commit 27de77cec985233bdf6546437b9761853265c505 ]
    
    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@xxxxxxxxxx
    Fixes: 11efd5cb04a1 ("openvswitch: Support conntrack zone limit")
    Cc: Pravin B Shelar <pshelar@xxxxxxx>
    Cc: Yi-Hung Wei <yihung.wei@xxxxxxxxx>
    Reported-by: syzbot+7ef50afd3a211f879112@xxxxxxxxxxxxxxxxxxxxxxxxx
    Signed-off-by: Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx>
    Acked-by: Pravin B Shelar <pshelar@xxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Stable-dep-of: 5ea7b72d4fac ("net: openvswitch: Fix Use-After-Free in ovs_ct_exit")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index 0777c8d416f1b..352e80e6cd75c 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -1837,7 +1837,8 @@ 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 0551915519d9f..db27a43f5c5ab 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -2390,8 +2390,10 @@ 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);