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NFSd: set nfsd_serv to NULL after service destruction
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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>
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Stanislav Kinsbursky authored and J. Bruce Fields committed Jul 25, 2012
1 parent 19f7e2c commit 57c8b13
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Showing 2 changed files with 7 additions and 5 deletions.
2 changes: 2 additions & 0 deletions fs/nfsd/nfsd.h
Original file line number Diff line number Diff line change
Expand Up @@ -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)
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10 changes: 5 additions & 5 deletions fs/nfsd/nfssvc.c
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -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) {
Expand All @@ -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;
Expand Down Expand Up @@ -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);
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