[Devel] [PATCH RHEL7 COMMIT] ms/lockd: lost rollback of set_grace_period() in lockd_down_net()

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-862.3.2.vz7.61.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-862.3.2.vz7.61.12
------>
commit 9740a12cc5e25a789afe0a8705de2a363b009798
Author: Vasily Averin <vvs at virtuozzo.com>
Date:   Thu Nov 2 13:03:42 2017 +0300

    ms/lockd: lost rollback of set_grace_period() in lockd_down_net()
    
    Commit efda760fe95ea ("lockd: fix lockd shutdown race") is incorrect,
    it removes lockd_manager and disarm grace_period_end for init_net only.
    
    If nfsd was started from another net namespace lockd_up_net() calls
    set_grace_period() that adds lockd_manager into per-netns list
    and queues grace_period_end delayed work.
    
    These action should be reverted in lockd_down_net().
    Otherwise it can lead to double list_add on after restart nfsd in netns,
    and to use-after-free if non-disarmed delayed work will be executed after netns destroy.
    
    Fixes: efda760fe95e ("lockd: fix lockd shutdown race")
    Cc: stable at vger.kernel.org
    Signed-off-by: Vasily Averin <vvs at virtuozzo.com>
    Signed-off-by: J. Bruce Fields <bfields at redhat.com>
    
    This patch should actually fix
    https://jira.sw.ru/browse/PSBM-86390
    
    (cherry picked from commit 3a2b19d1ee5633f76ae8a88da7bc039a5d1732aa)
    Signed-off-by: Vasily Averin <vvs at virtuozzo.com>
---
 fs/lockd/svc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index b52fd0feeac6..d2cffb3bbec3 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -278,6 +278,8 @@ static void lockd_down_net(struct svc_serv *serv, struct net *net)
 	if (ln->nlmsvc_users) {
 		if (--ln->nlmsvc_users == 0) {
 			nlm_shutdown_hosts_net(net);
+			cancel_delayed_work_sync(&ln->grace_period_end);
+			locks_end_grace(&ln->lockd_manager);
 			svc_shutdown_net(serv, net);
 			dprintk("lockd_down_net: per-net data destroyed; net=%p\n", net);
 		}