2017-10-20 14:33:21

by Vasily Averin

Subject: [PATCH v2] lockd: double unregister of inetaddr notifiers

v2: reported to stable@ because it fixes backported patch.

lockd_up() can call lockd_unregister_notifiers twice:
inside lockd_start_svc() when it calls lockd_svc_exit_thread()
and then in error path of lockd_up()

Patch forces lockd_start_svc() to unregister notifiers in all error cases
and removes extra unregister in error path of lockd_up().

Fixes: cb7d224f82e4 "lockd: unregister notifier blocks if the service ..."
Signed-off-by: Vasily Averin <[email protected]>
---
fs/lockd/svc.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index b995bdc..f04ecfc 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -369,6 +369,7 @@ static int lockd_start_svc(struct svc_serv *serv)
printk(KERN_WARNING
"lockd_up: svc_rqst allocation failed, error=%d\n",
error);
+ lockd_unregister_notifiers();
goto out_rqst;
}

@@ -459,13 +460,16 @@ int lockd_up(struct net *net)
}

error = lockd_up_net(serv, net);
- if (error < 0)
- goto err_net;
+ if (error < 0) {
+ lockd_unregister_notifiers();
+ goto err_put;
+ }

error = lockd_start_svc(serv);
- if (error < 0)
- goto err_start;
-
+ if (error < 0) {
+ lockd_down_net(serv, net);
+ goto err_put;
+ }
nlmsvc_users++;
/*
* Note: svc_serv structures have an initial use count of 1,
@@ -476,12 +480,6 @@ int lockd_up(struct net *net)
err_create:
mutex_unlock(&nlmsvc_mutex);
return error;
-
-err_start:
- lockd_down_net(serv, net);
-err_net:
- lockd_unregister_notifiers();
- goto err_put;
}
EXPORT_SYMBOL_GPL(lockd_up);

--
2.7.4

2017-10-20 17:03:41

by Jeff Layton

Subject: Re: [PATCH v2] lockd: double unregister of inetaddr notifiers

On Fri, 2017-10-20 at 17:33 +0300, Vasily Averin wrote:
> v2: reported to stable@ because it fixes backported patch.
>
> lockd_up() can call lockd_unregister_notifiers twice:
> inside lockd_start_svc() when it calls lockd_svc_exit_thread()
> and then in error path of lockd_up()
>
> Patch forces lockd_start_svc() to unregister notifiers in all error cases
> and removes extra unregister in error path of lockd_up().
>
> Fixes: cb7d224f82e4 "lockd: unregister notifier blocks if the service ..."
> Signed-off-by: Vasily Averin <[email protected]>
> ---
> fs/lockd/svc.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
> index b995bdc..f04ecfc 100644
> --- a/fs/lockd/svc.c
> +++ b/fs/lockd/svc.c
> @@ -369,6 +369,7 @@ static int lockd_start_svc(struct svc_serv *serv)
> printk(KERN_WARNING
> "lockd_up: svc_rqst allocation failed, error=%d\n",
> error);
> + lockd_unregister_notifiers();
> goto out_rqst;
> }
>
> @@ -459,13 +460,16 @@ int lockd_up(struct net *net)
> }
>
> error = lockd_up_net(serv, net);
> - if (error < 0)
> - goto err_net;
> + if (error < 0) {
> + lockd_unregister_notifiers();
> + goto err_put;
> + }
>
> error = lockd_start_svc(serv);
> - if (error < 0)
> - goto err_start;
> -
> + if (error < 0) {
> + lockd_down_net(serv, net);
> + goto err_put;
> + }
> nlmsvc_users++;
> /*
> * Note: svc_serv structures have an initial use count of 1,
> @@ -476,12 +480,6 @@ int lockd_up(struct net *net)
> err_create:
> mutex_unlock(&nlmsvc_mutex);
> return error;
> -
> -err_start:
> - lockd_down_net(serv, net);
> -err_net:
> - lockd_unregister_notifiers();
> - goto err_put;
> }
> EXPORT_SYMBOL_GPL(lockd_up);
>

I think this looks right. I really do hate the way that the notifier
handling is sprinkled all over the place in this code (not a comment on
your patch so much as the lockd code in general). I don't see a better
way to do it right offhand though.

Reviewed-by: Jeff Layton <[email protected]>

2017-10-20 18:54:38

by J. Bruce Fields

Subject: Re: [PATCH v2] lockd: double unregister of inetaddr notifiers

Thanks, applying for 3.15 with a stable cc.

--b.

On Fri, Oct 20, 2017 at 01:03:37PM -0400, Jeff Layton wrote:
> On Fri, 2017-10-20 at 17:33 +0300, Vasily Averin wrote:
> > v2: reported to stable@ because it fixes backported patch.
> >
> > lockd_up() can call lockd_unregister_notifiers twice:
> > inside lockd_start_svc() when it calls lockd_svc_exit_thread()
> > and then in error path of lockd_up()
> >
> > Patch forces lockd_start_svc() to unregister notifiers in all error cases
> > and removes extra unregister in error path of lockd_up().
> >
> > Fixes: cb7d224f82e4 "lockd: unregister notifier blocks if the service ..."
> > Signed-off-by: Vasily Averin <[email protected]>
> > ---
> > fs/lockd/svc.c | 20 +++++++++-----------
> > 1 file changed, 9 insertions(+), 11 deletions(-)
> >
> > diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
> > index b995bdc..f04ecfc 100644
> > --- a/fs/lockd/svc.c
> > +++ b/fs/lockd/svc.c
> > @@ -369,6 +369,7 @@ static int lockd_start_svc(struct svc_serv *serv)
> > printk(KERN_WARNING
> > "lockd_up: svc_rqst allocation failed, error=%d\n",
> > error);
> > + lockd_unregister_notifiers();
> > goto out_rqst;
> > }
> >
> > @@ -459,13 +460,16 @@ int lockd_up(struct net *net)
> > }
> >
> > error = lockd_up_net(serv, net);
> > - if (error < 0)
> > - goto err_net;
> > + if (error < 0) {
> > + lockd_unregister_notifiers();
> > + goto err_put;
> > + }
> >
> > error = lockd_start_svc(serv);
> > - if (error < 0)
> > - goto err_start;
> > -
> > + if (error < 0) {
> > + lockd_down_net(serv, net);
> > + goto err_put;
> > + }
> > nlmsvc_users++;
> > /*
> > * Note: svc_serv structures have an initial use count of 1,
> > @@ -476,12 +480,6 @@ int lockd_up(struct net *net)
> > err_create:
> > mutex_unlock(&nlmsvc_mutex);
> > return error;
> > -
> > -err_start:
> > - lockd_down_net(serv, net);
> > -err_net:
> > - lockd_unregister_notifiers();
> > - goto err_put;
> > }
> > EXPORT_SYMBOL_GPL(lockd_up);
> >
>
> I think this looks right. I really do hate the way that the notifier
> handling is sprinkled all over the place in this code (not a comment on
> your patch so much as the lockd code in general). I don't see a better
> way to do it right offhand though.
>
> Reviewed-by: Jeff Layton <[email protected]>