NFSd: set nfsd_serv to NULL after service destruction

In nfsd_destroy():

	if (destroy)
		svc_shutdown_net(nfsd_serv, net);
	svc_destroy(nfsd_server);

svc_shutdown_net(nfsd_serv, net) calls nfsd_last_thread(), which sets
nfsd_serv to NULL, causing a NULL dereference on the following line.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

2 files changed, 7 insertions, 5 deletions

diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 7b248a24d5c5..2244222368ab 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -82,6 +82,8 @@ static inline void nfsd_destroy(struct net *net)
         if (destroy)
                 svc_shutdown_net(nfsd_serv, net);
         svc_destroy(nfsd_serv);
+        if (destroy)
+                nfsd_serv = NULL;
 }
 
 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 8621e36ce8dd..240473cb708f 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -254,8 +254,6 @@ static void nfsd_shutdown(void)
 
 static void nfsd_last_thread(struct svc_serv *serv, struct net *net)
 {
-        /* When last nfsd thread exits we need to do some clean-up */
-        nfsd_serv = NULL;
         nfsd_shutdown();
 
         svc_rpcb_cleanup(serv, net);
@@ -332,6 +330,7 @@ static int nfsd_get_default_max_blksize(void)
 int nfsd_create_serv(void)
 {
         int error;
+        struct net *net = current->nsproxy->net_ns;
 
         WARN_ON(!mutex_is_locked(&nfsd_mutex));
         if (nfsd_serv) {
@@ -346,7 +345,7 @@ int nfsd_create_serv(void)
         if (nfsd_serv == NULL)
                 return -ENOMEM;
 
-        error = svc_bind(nfsd_serv, current->nsproxy->net_ns);
+        error = svc_bind(nfsd_serv, net);
         if (error < 0) {
                 svc_destroy(nfsd_serv);
                 return error;
@@ -557,12 +556,13 @@ nfsd(void *vrqstp)
         nfsdstats.th_cnt --;
 
 out:
-        if (rqstp->rq_server->sv_nrthreads == 1)
-                svc_shutdown_net(rqstp->rq_server, &init_net);
+        rqstp->rq_server = NULL;
 
         /* Release the thread */
         svc_exit_thread(rqstp);
 
+        nfsd_destroy(&init_net);
+
         /* Release module */
         mutex_unlock(&nfsd_mutex);
         module_put_and_exit(0);