[PATCH 0/2] nfsd: backport fixes for 3.5 kernel

[PATCH 0/2] nfsd: backport fixes for 3.5 kernel

[Stanislav Kinsbursky]

Hello.
These two patches fixes existent NULL pointer dereference problem in 3.5.3
kernel in case of some error occured during NFSd service start.

Upstream commits:
19f7e2ca44dfc3c1b3f499fc46801f98d403500f 
57c8b13e3cd0f94944c9691ce7f58e5fcef8a12d


The following series implements...

---

Stanislav Kinsbursky (2):
      NFSd: introduce nfsd_destroy() helper
      NFSd: set nfsd_serv to NULL after service destruction


 fs/nfsd/nfsctl.c |    8 ++------
 fs/nfsd/nfsd.h   |   11 +++++++++++
 fs/nfsd/nfssvc.c |   24 ++++++++----------------
 3 files changed, 21 insertions(+), 22 deletions(-)

[PATCH 1/2] NFSd: introduce nfsd_destroy() helper

[Stanislav Kinsbursky]

upstream commit 19f7e2ca44dfc3c1b3f499fc46801f98d403500f

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/nfsd/nfsctl.c |    8 ++------
 fs/nfsd/nfsd.h   |    9 +++++++++
 fs/nfsd/nfssvc.c |   14 +++-----------
 3 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index c55298e..fa49cff 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -673,9 +673,7 @@ static ssize_t __write_ports_addfd(char *buf)
 
 	err = svc_addsock(nfsd_serv, fd, buf, SIMPLE_TRANSACTION_LIMIT);
 	if (err < 0) {
-		if (nfsd_serv->sv_nrthreads == 1)
-			svc_shutdown_net(nfsd_serv, net);
-		svc_destroy(nfsd_serv);
+		nfsd_destroy(net);
 		return err;
 	}
 
@@ -744,9 +742,7 @@ out_close:
 		svc_xprt_put(xprt);
 	}
 out_err:
-	if (nfsd_serv->sv_nrthreads == 1)
-		svc_shutdown_net(nfsd_serv, net);
-	svc_destroy(nfsd_serv);
+	nfsd_destroy(net);
 	return err;
 }
 
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 1671429..e3339ca 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -73,6 +73,15 @@ int		nfsd_nrpools(void);
 int		nfsd_get_nrthreads(int n, int *);
 int		nfsd_set_nrthreads(int n, int *);
 
+static inline void nfsd_destroy(struct net *net)
+{
+	int destroy = (nfsd_serv->sv_nrthreads == 1);
+
+	if (destroy)
+		svc_shutdown_net(nfsd_serv, net);
+	svc_destroy(nfsd_serv);
+}
+
 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 #ifdef CONFIG_NFSD_V2_ACL
 extern struct svc_version nfsd_acl_version2;
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index d63c097..e866af4 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -429,11 +429,7 @@ int nfsd_set_nrthreads(int n, int *nthreads)
 		if (err)
 			break;
 	}
-
-	if (nfsd_serv->sv_nrthreads == 1)
-		svc_shutdown_net(nfsd_serv, net);
-	svc_destroy(nfsd_serv);
-
+	nfsd_destroy(net);
 	return err;
 }
 
@@ -480,9 +476,7 @@ out_shutdown:
 	if (error < 0 && !nfsd_up_before)
 		nfsd_shutdown();
 out_destroy:
-	if (nfsd_serv->sv_nrthreads == 1)
-		svc_shutdown_net(nfsd_serv, net);
-	svc_destroy(nfsd_serv);		/* Release server */
+	nfsd_destroy(net);		/* Release server */
 out:
 	mutex_unlock(&nfsd_mutex);
 	return error;
@@ -684,9 +678,7 @@ int nfsd_pool_stats_release(struct inode *inode, struct file *file)
 
 	mutex_lock(&nfsd_mutex);
 	/* this function really, really should have been called svc_put() */
-	if (nfsd_serv->sv_nrthreads == 1)
-		svc_shutdown_net(nfsd_serv, net);
-	svc_destroy(nfsd_serv);
+	nfsd_destroy(net);
 	mutex_unlock(&nfsd_mutex);
 	return ret;
 }

[PATCH 2/2] NFSd: set nfsd_serv to NULL after service destruction

[Stanislav Kinsbursky]

upstream commit 57c8b13e3cd0f94944c9691ce7f58e5fcef8a12d

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>
---
 fs/nfsd/nfsd.h   |    2 ++
 fs/nfsd/nfssvc.c |   10 +++++-----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index e3339ca..1336a65 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -80,6 +80,8 @@ 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 e866af4..5f4b8f2 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -256,8 +256,6 @@ 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);
@@ -334,6 +332,7 @@ 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) {
@@ -348,7 +347,7 @@ 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;
@@ -559,12 +558,13 @@ 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);

Re: [PATCH 0/2] nfsd: backport fixes for 3.5 kernel

[J. Bruce Fields]

On Fri, Sep 14, 2012 at 12:25:17PM +0400, Stanislav Kinsbursky wrote:
> Hello.
> These two patches fixes existent NULL pointer dereference problem in 3.5.3
> kernel in case of some error occured during NFSd service start.
> 
> Upstream commits:
> 19f7e2ca44dfc3c1b3f499fc46801f98d403500f 
> 57c8b13e3cd0f94944c9691ce7f58e5fcef8a12d

Thanks.  Ack to including both of these in stable releases.

--b.

> 
> 
> The following series implements...
> 
> ---
> 
> Stanislav Kinsbursky (2):
>       NFSd: introduce nfsd_destroy() helper
>       NFSd: set nfsd_serv to NULL after service destruction
> 
> 
>  fs/nfsd/nfsctl.c |    8 ++------
>  fs/nfsd/nfsd.h   |   11 +++++++++++
>  fs/nfsd/nfssvc.c |   24 ++++++++----------------
>  3 files changed, 21 insertions(+), 22 deletions(-)
> 

Re: [PATCH 0/2] nfsd: backport fixes for 3.5 kernel

[Greg KH]

On Mon, Sep 17, 2012 at 11:01:05AM -0400, J. Bruce Fields wrote:
> On Fri, Sep 14, 2012 at 12:25:17PM +0400, Stanislav Kinsbursky wrote:
> > Hello.
> > These two patches fixes existent NULL pointer dereference problem in 3.5.3
> > kernel in case of some error occured during NFSd service start.
> > 
> > Upstream commits:
> > 19f7e2ca44dfc3c1b3f499fc46801f98d403500f 
> > 57c8b13e3cd0f94944c9691ce7f58e5fcef8a12d
> 
> Thanks.  Ack to including both of these in stable releases.

Now applied, also to the 3.4.y stable series.

greg k-h