The delete callback can be called either via the unregister function or
from the transport directly. Thus it is necessary ensure resources are
not freed multiple times.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
---
 drivers/nvme/target/fcloop.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/nvme/target/fcloop.c b/drivers/nvme/target/fcloop.c
index de23f0bc5599b6f8dd5c3713dd38c952e6fdda28..06f42da6a0335c53ae319133119d057aab12e07e 100644
--- a/drivers/nvme/target/fcloop.c
+++ b/drivers/nvme/target/fcloop.c
@@ -215,6 +215,8 @@ struct fcloop_lport_priv {
 	struct fcloop_lport *lport;
 };
 
+#define PORT_DELETE	0
+
 struct fcloop_rport {
 	struct nvme_fc_remote_port	*remoteport;
 	struct nvmet_fc_target_port	*targetport;
@@ -223,6 +225,7 @@ struct fcloop_rport {
 	spinlock_t			lock;
 	struct list_head		ls_list;
 	struct work_struct		ls_work;
+	unsigned long			flags;
 };
 
 struct fcloop_tport {
@@ -233,6 +236,7 @@ struct fcloop_tport {
 	spinlock_t			lock;
 	struct list_head		ls_list;
 	struct work_struct		ls_work;
+	unsigned long			flags;
 };
 
 struct fcloop_nport {
@@ -1062,14 +1066,20 @@ static void
 fcloop_remoteport_delete(struct nvme_fc_remote_port *remoteport)
 {
 	struct fcloop_rport *rport = remoteport->private;
+	bool delete_port = true;
 	unsigned long flags;
 
 	flush_work(&rport->ls_work);
 
 	spin_lock_irqsave(&fcloop_lock, flags);
+	if (test_and_set_bit(PORT_DELETE, &rport->flags))
+		delete_port = false;
 	rport->nport->rport = NULL;
 	spin_unlock_irqrestore(&fcloop_lock, flags);
 
+	if (!delete_port)
+		return;
+
 	/* nport ref put: rport */
 	fcloop_nport_put(rport->nport);
 }
@@ -1078,14 +1088,20 @@ static void
 fcloop_targetport_delete(struct nvmet_fc_target_port *targetport)
 {
 	struct fcloop_tport *tport = targetport->private;
+	bool delete_port = true;
 	unsigned long flags;
 
 	flush_work(&tport->ls_work);
 
 	spin_lock_irqsave(&fcloop_lock, flags);
+	if (test_and_set_bit(PORT_DELETE, &tport->flags))
+		delete_port = false;
 	tport->nport->tport = NULL;
 	spin_unlock_irqrestore(&fcloop_lock, flags);
 
+	if (!delete_port)
+		return;
+
 	complete(&tport->nport->tport_unreg_done);
 
 	/* nport ref put: tport */
@@ -1394,6 +1410,7 @@ fcloop_create_remote_port(struct device *dev, struct device_attribute *attr,
 	rport->nport = nport;
 	rport->lport = nport->lport;
 	nport->rport = rport;
+	rport->flags = 0;
 	spin_lock_init(&rport->lock);
 	INIT_WORK(&rport->ls_work, fcloop_rport_lsrqst_work);
 	INIT_LIST_HEAD(&rport->ls_list);
@@ -1492,6 +1509,7 @@ fcloop_create_target_port(struct device *dev, struct device_attribute *attr,
 	tport->nport = nport;
 	tport->lport = nport->lport;
 	nport->tport = tport;
+	tport->flags = 0;
 	spin_lock_init(&tport->lock);
 	INIT_WORK(&tport->ls_work, fcloop_tport_lsrqst_work);
 	INIT_LIST_HEAD(&tport->ls_list);

-- 
2.48.1

On Tue, Mar 18, 2025 at 11:40:03AM +0100, Daniel Wagner wrote:
>  };
>  
> +#define PORT_DELETE	0

The way I read the code this should be PORT_DELETED?

Also maybe add a little comment, once we grow more flags that really
helps.

On 3/18/25 11:40, Daniel Wagner wrote:
> The delete callback can be called either via the unregister function or
> from the transport directly. Thus it is necessary ensure resources are
> not freed multiple times.
> 
> Signed-off-by: Daniel Wagner <wagi@kernel.org>
> ---
>   drivers/nvme/target/fcloop.c | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/nvme/target/fcloop.c b/drivers/nvme/target/fcloop.c
> index de23f0bc5599b6f8dd5c3713dd38c952e6fdda28..06f42da6a0335c53ae319133119d057aab12e07e 100644
> --- a/drivers/nvme/target/fcloop.c
> +++ b/drivers/nvme/target/fcloop.c
> @@ -215,6 +215,8 @@ struct fcloop_lport_priv {
>   	struct fcloop_lport *lport;
>   };
>   
> +#define PORT_DELETE	0
> +
>   struct fcloop_rport {
>   	struct nvme_fc_remote_port	*remoteport;
>   	struct nvmet_fc_target_port	*targetport;
> @@ -223,6 +225,7 @@ struct fcloop_rport {
>   	spinlock_t			lock;
>   	struct list_head		ls_list;
>   	struct work_struct		ls_work;
> +	unsigned long			flags;
>   };
>   
>   struct fcloop_tport {
> @@ -233,6 +236,7 @@ struct fcloop_tport {
>   	spinlock_t			lock;
>   	struct list_head		ls_list;
>   	struct work_struct		ls_work;
> +	unsigned long			flags;
>   };
>   
>   struct fcloop_nport {
> @@ -1062,14 +1066,20 @@ static void
>   fcloop_remoteport_delete(struct nvme_fc_remote_port *remoteport)
>   {
>   	struct fcloop_rport *rport = remoteport->private;
> +	bool delete_port = true;
>   	unsigned long flags;
>   
>   	flush_work(&rport->ls_work);
>   
>   	spin_lock_irqsave(&fcloop_lock, flags);
> +	if (test_and_set_bit(PORT_DELETE, &rport->flags))
> +		delete_port = false;
>   	rport->nport->rport = NULL;
>   	spin_unlock_irqrestore(&fcloop_lock, flags);
>   
Can't you just check for a NULL rport->nport->rport pointer
and do away with the PORT_DELETE flag?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich

On Tue, Mar 18, 2025 at 12:15:04PM +0100, Hannes Reinecke wrote:
> >   fcloop_remoteport_delete(struct nvme_fc_remote_port *remoteport)
> >   {
> >   	struct fcloop_rport *rport = remoteport->private;
> > +	bool delete_port = true;
> >   	unsigned long flags;
> >   	flush_work(&rport->ls_work);
> >   	spin_lock_irqsave(&fcloop_lock, flags);
> > +	if (test_and_set_bit(PORT_DELETE, &rport->flags))
> > +		delete_port = false;
> >   	rport->nport->rport = NULL;
> >   	spin_unlock_irqrestore(&fcloop_lock, flags);
> Can't you just check for a NULL rport->nport->rport pointer
> and do away with the PORT_DELETE flag?

Unfortunately, nport->rport is also set to NULL in __unlink_remote_port
and __unlink_target_port. If we would just update the pointer here, it
would be possible.

I played a bit around when to clear the nport->rport pointer but it
didn't work. There were always some UAFs or NULL pointer accesses. With
the flags I was able to get it fixed. I am not insisting on this
solution, just trying to explain why I choosed it.