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    Subject[PATCH 4.9 29/33] lockd: lost rollback of set_grace_period() in lockd_down_net()
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Vasily Averin <vvs@virtuozzo.com>

    commit 3a2b19d1ee5633f76ae8a88da7bc039a5d1732aa upstream.

    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@vger.kernel.org
    Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
    Signed-off-by: J. Bruce Fields <bfields@redhat.com>
    Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/lockd/svc.c | 2 ++
    1 file changed, 2 insertions(+)

    --- a/fs/lockd/svc.c
    +++ b/fs/lockd/svc.c
    @@ -274,6 +274,8 @@ static void lockd_down_net(struct svc_se
    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);
    }

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