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[PATCH] NFSd: set nfsd_serv to NULL after service destruction [message #46409] Fri, 18 May 2012 15:26 Go to next message
Stanislav Kinsbursky is currently offline  Stanislav Kinsbursky
Messages: 683
Registered: October 2011
Senior Member
Otherwise we will get NULL pointer dereference after
svc_shutdown_net->sv_shutdown (nfsd_last_thread) call.
This looks safe, because all such operations (svc_destroy) are performed with
nfsd_mutex being held.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
---
fs/nfsd/nfsctl.c | 4 ++--
fs/nfsd/nfsd.h | 6 ++++++
fs/nfsd/nfssvc.c | 10 ++++------
3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index c55298e..82cca1e 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -675,7 +675,7 @@ static ssize_t __write_ports_addfd(char *buf)
if (err < 0) {
if (nfsd_serv->sv_nrthreads == 1)
svc_shutdown_net(nfsd_serv, net);
- svc_destroy(nfsd_serv);
+ nfsd_destroy();
return err;
}

@@ -746,7 +746,7 @@ out_close:
out_err:
if (nfsd_serv->sv_nrthreads == 1)
svc_shutdown_net(nfsd_serv, net);
- svc_destroy(nfsd_serv);
+ nfsd_destroy();
return err;
}

diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 1671429..35db369 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -73,6 +73,12 @@ int nfsd_nrpools(void);
int nfsd_get_nrthreads(int n, int *);
int nfsd_set_nrthreads(int n, int *);

+static inline void nfsd_destroy(void)
+{
+ svc_destroy(nfsd_serv);
+ nfsd_serv = NULL;
+}
+
#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 ee709fc..ab89fe0 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);
@@ -348,7 +346,7 @@ int nfsd_create_serv(void)

error = svc_bind(nfsd_serv, current->nsproxy->net_ns);
if (error < 0) {
- svc_destroy(nfsd_serv);
+ nfsd_destroy();
return error;
}

@@ -430,7 +428,7 @@ int nfsd_set_nrthreads(int n, int *nthreads)

if (nfsd_serv->sv_nrthreads == 1)
svc_shutdown_net(nfsd_serv, net);
- svc_destroy(nfsd_serv);
+ nfsd_destroy();

return err;
}
@@ -480,7 +478,7 @@ out_shutdown:
out_destroy:
if (nfsd_serv->sv_nrthreads == 1)
svc_shutdown_net(nfsd_serv, net);
- svc_destroy(nfsd_serv); /* Release server */
+ nfsd_destroy(); /* Release server */
out:
mutex_unlock(&nfsd_mutex);
return error;
@@ -684,7 +682,7 @@ int nfsd_pool_stats_release(struct inode *inode, struct file *file)
/* 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();
mutex_unlock(&nfsd_mutex);
return ret;
}

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Re: [PATCH] NFSd: set nfsd_serv to NULL after service destruction [message #46494 is a reply to message #46409] Wed, 23 May 2012 21:52 Go to previous message
bfields is currently offline  bfields
Messages: 107
Registered: September 2007
Senior Member
On Fri, May 18, 2012 at 07:26:02PM +0400, Stanislav Kinsbursky wrote:
> Otherwise we will get NULL pointer dereference after
> svc_shutdown_net->sv_shutdown (nfsd_last_thread) call.
> This looks safe, because all such operations (svc_destroy) are performed with
> nfsd_mutex being held.
>
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
> ---
> fs/nfsd/nfsctl.c | 4 ++--
> fs/nfsd/nfsd.h | 6 ++++++
> fs/nfsd/nfssvc.c | 10 ++++------
> 3 files changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index c55298e..82cca1e 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -675,7 +675,7 @@ static ssize_t __write_ports_addfd(char *buf)
> if (err < 0) {
> if (nfsd_serv->sv_nrthreads == 1)
> svc_shutdown_net(nfsd_serv, net);
> - svc_destroy(nfsd_serv);
> + nfsd_destroy();

The server could still be running here. We don't want to set nfsd_serv
to NULL.

--b.

> return err;
> }
>
> @@ -746,7 +746,7 @@ out_close:
> out_err:
> if (nfsd_serv->sv_nrthreads == 1)
> svc_shutdown_net(nfsd_serv, net);
> - svc_destroy(nfsd_serv);
> + nfsd_destroy();
> return err;
> }
>
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index 1671429..35db369 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -73,6 +73,12 @@ int nfsd_nrpools(void);
> int nfsd_get_nrthreads(int n, int *);
> int nfsd_set_nrthreads(int n, int *);
>
> +static inline void nfsd_destroy(void)
> +{
> + svc_destroy(nfsd_serv);
> + nfsd_serv = NULL;
> +}
> +
> #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 ee709fc..ab89fe0 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);
> @@ -348,7 +346,7 @@ int nfsd_create_serv(void)
>
> error = svc_bind(nfsd_serv, current->nsproxy->net_ns);
> if (error < 0) {
> - svc_destroy(nfsd_serv);
> + nfsd_destroy();
> return error;
> }
>
> @@ -430,7 +428,7 @@ int nfsd_set_nrthreads(int n, int *nthreads)
>
> if (nfsd_serv->sv_nrthreads == 1)
> svc_shutdown_net(nfsd_serv, net);
> - svc_destroy(nfsd_serv);
> + nfsd_destroy();
>
> return err;
> }
> @@ -480,7 +478,7 @@ out_shutdown:
> out_destroy:
> if (nfsd_serv->sv_nrthreads == 1)
> svc_shutdown_net(nfsd_serv, net);
> - svc_destroy(nfsd_serv); /* Release server */
> + nfsd_destroy(); /* Release server */
> out:
> mutex_unlock(&nfsd_mutex);
> return error;
> @@ -684,7 +682,7 @@ int nfsd_pool_stats_release(struct inode *inode, struct file *file)
> /* 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();
> mutex_unlock(&nfsd_mutex);
> return ret;
> }
>

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