[PATCH]: net: hso: do not call unregister if not registered

[PATCH]: net: hso: do not call unregister if not registered

[Yavuz, Tuba]

On an error path inside the hso_create_net_device function of the hso
driver, hso_free_net_device gets called. This causes potentially a
negative reference count in the net device if register_netdev has not
been called yet as hso_free_net_device calls unregister_netdev
regardless. I think the driver should distinguish these cases and call
unregister_netdev only if register_netdev has been called.

Signed-off-by: Tuba Yavuz <tuba@ece.ufl.edu>
---

--- linux-stable/drivers/net/usb/hso.c.orig     2019-01-27 14:45:58.232683119 -0500
+++ linux-stable/drivers/net/usb/hso.c  2019-02-05 17:54:17.056496019 -0500
@@ -2377,7 +2377,9 @@ static void hso_free_net_device(struct h
 
        remove_net_device(hso_net->parent);
 
-       if (hso_net->net)
+       if (hso_net->net &&
+           hso_net->net->reg_state == NETREG_REGISTERED
+          )
                unregister_netdev(hso_net->net);
 
        /* start freeing */

Re: [PATCH]: net: hso: do not call unregister if not registered

[David Miller]

From: "Yavuz, Tuba" <tuba@ece.ufl.edu>
Date: Tue, 5 Feb 2019 23:01:25 +0000

> 
> 
> On an error path inside the hso_create_net_device function of the hso
> driver, hso_free_net_device gets called. This causes potentially a
> negative reference count in the net device if register_netdev has not
> been called yet as hso_free_net_device calls unregister_netdev
> regardless. I think the driver should distinguish these cases and call
> unregister_netdev only if register_netdev has been called.
> 
> Signed-off-by: Tuba Yavuz <tuba@ece.ufl.edu>
> ---
> 
> --- linux-stable/drivers/net/usb/hso.c.orig     2019-01-27 14:45:58.232683119 -0500
> +++ linux-stable/drivers/net/usb/hso.c  2019-02-05 17:54:17.056496019 -0500
> @@ -2377,7 +2377,9 @@ static void hso_free_net_device(struct h
>  
>         remove_net_device(hso_net->parent);
>  
> -       if (hso_net->net)
> +       if (hso_net->net &&
> +           hso_net->net->reg_state == NETREG_REGISTERED
> +          )

This is not formatted correctly, the final closing ')' should end the
previous line, like this:

       if (hso_net->net &&
           hso_net->net->reg_state == NETREG_REGISTERED)

Re: [PATCH]: net: hso: do not call unregister if not registered

[Yavuz, Tuba]

This is surprising as I got total: 0 errors, 0 warnings, 0 checks, 10 lines checked.

Anyhow, I'll submit as suggested.

Best,


Tuba Yavuz, Ph.D.
Assistant Professor
Electrical and Computer Engineering Department
University of Florida
Gainesville, FL 32611
Webpage: http://www.tuba.ece.ufl.edu/
Email: tuba@ece.ufl.edu
Phone: (352) 846 0202

________________________________________
From: David Miller <davem@davemloft.net>
Sent: Tuesday, February 5, 2019 7:36 PM
To: Yavuz, Tuba
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH]: net: hso: do not call unregister if not registered

From: "Yavuz, Tuba" <tuba@ece.ufl.edu>
Date: Tue, 5 Feb 2019 23:01:25 +0000

>
>
> On an error path inside the hso_create_net_device function of the hso
> driver, hso_free_net_device gets called. This causes potentially a
> negative reference count in the net device if register_netdev has not
> been called yet as hso_free_net_device calls unregister_netdev
> regardless. I think the driver should distinguish these cases and call
> unregister_netdev only if register_netdev has been called.
>
> Signed-off-by: Tuba Yavuz <tuba@ece.ufl.edu>
> ---
>
> --- linux-stable/drivers/net/usb/hso.c.orig     2019-01-27 14:45:58.232683119 -0500
> +++ linux-stable/drivers/net/usb/hso.c  2019-02-05 17:54:17.056496019 -0500
> @@ -2377,7 +2377,9 @@ static void hso_free_net_device(struct h
>
>         remove_net_device(hso_net->parent);
>
> -       if (hso_net->net)
> +       if (hso_net->net &&
> +           hso_net->net->reg_state == NETREG_REGISTERED
> +          )

This is not formatted correctly, the final closing ')' should end the
previous line, like this:

       if (hso_net->net &&
           hso_net->net->reg_state == NETREG_REGISTERED)

[PATCH] net: hso: do not call unregister if not registered

[Yavuz, Tuba]

On an error path inside the hso_create_net_device function of the hso
driver, hso_free_net_device gets called. This causes potentially a
negative reference count in the net device if register_netdev has not
been called yet as hso_free_net_device calls unregister_netdev
regardless. I think the driver should distinguish these cases and call
unregister_netdev only if register_netdev has been called.

Signed-off-by: Tuba Yavuz <tuba@ece.ufl.edu>
---

--- linux-stable/drivers/net/usb/hso.c.orig	2019-01-27 14:45:58.232683119 -0500
+++ linux-stable/drivers/net/usb/hso.c	2019-02-05 17:54:17.056496019 -0500
@@ -2377,7 +2377,9 @@ static void hso_free_net_device(struct h
 
 	remove_net_device(hso_net->parent);
 
-	if (hso_net->net)
+	if (hso_net->net &&
+	    hso_net->net->reg_state == NETREG_REGISTERED)
 		unregister_netdev(hso_net->net);
 
 	/* start freeing */