[PATCH] net: hso: fix NULL-deref on disconnect regression

[PATCH] net: hso: fix NULL-deref on disconnect regression

[Johan Hovold]

Commit 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device
unregistration") fixed the racy minor allocation reported by syzbot, but
introduced an unconditional NULL-pointer dereference on every disconnect
instead.

Specifically, the serial device table must no longer be accessed after
the minor has been released by hso_serial_tty_unregister().

Fixes: 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device unregistration")
Cc: stable@vger.kernel.org
Cc: Anirudh Rayabharam <mail@anirudhrb.com>
Reported-by: Leonardo Antoniazzi <leoanto@aruba.it>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/usb/hso.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 9bc58e64b5b7..3ef4b2841402 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -3104,7 +3104,7 @@ static void hso_free_interface(struct usb_interface *interface)
 			cancel_work_sync(&serial_table[i]->async_put_intf);
 			cancel_work_sync(&serial_table[i]->async_get_intf);
 			hso_serial_tty_unregister(serial);
-			kref_put(&serial_table[i]->ref, hso_serial_ref_free);
+			kref_put(&serial->parent->ref, hso_serial_ref_free);
 		}
 	}
 
-- 
2.26.3

Re: [PATCH] net: hso: fix NULL-deref on disconnect regression

[Leonardo Antoniazzi]

On Mon, 26 Apr 2021 10:11:49 +0200
Johan Hovold <johan@kernel.org> wrote:

> Commit 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device
> unregistration") fixed the racy minor allocation reported by syzbot, but
> introduced an unconditional NULL-pointer dereference on every disconnect
> instead.
> 
> Specifically, the serial device table must no longer be accessed after
> the minor has been released by hso_serial_tty_unregister().
> 
> Fixes: 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device unregistration")
> Cc: stable@vger.kernel.org
> Cc: Anirudh Rayabharam <mail@anirudhrb.com>
> Reported-by: Leonardo Antoniazzi <leoanto@aruba.it>
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
>  drivers/net/usb/hso.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
> index 9bc58e64b5b7..3ef4b2841402 100644
> --- a/drivers/net/usb/hso.c
> +++ b/drivers/net/usb/hso.c
> @@ -3104,7 +3104,7 @@ static void hso_free_interface(struct usb_interface *interface)
>  			cancel_work_sync(&serial_table[i]->async_put_intf);
>  			cancel_work_sync(&serial_table[i]->async_get_intf);
>  			hso_serial_tty_unregister(serial);
> -			kref_put(&serial_table[i]->ref, hso_serial_ref_free);
> +			kref_put(&serial->parent->ref, hso_serial_ref_free);
>  		}
>  	}
>  
> -- 
> 2.26.3
> 

hello,

the patch fix the problem

thanks

Re: [PATCH] net: hso: fix NULL-deref on disconnect regression

[Johan Hovold]

On Mon, Apr 26, 2021 at 11:29:11AM +0200, Leonardo Antoniazzi wrote:
> On Mon, 26 Apr 2021 10:11:49 +0200
> Johan Hovold <johan@kernel.org> wrote:
> 
> > Commit 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device
> > unregistration") fixed the racy minor allocation reported by syzbot, but
> > introduced an unconditional NULL-pointer dereference on every disconnect
> > instead.
> > 
> > Specifically, the serial device table must no longer be accessed after
> > the minor has been released by hso_serial_tty_unregister().
> > 
> > Fixes: 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device unregistration")
> > Cc: stable@vger.kernel.org
> > Cc: Anirudh Rayabharam <mail@anirudhrb.com>
> > Reported-by: Leonardo Antoniazzi <leoanto@aruba.it>
> > Signed-off-by: Johan Hovold <johan@kernel.org>
> > ---

> the patch fix the problem

Thanks for confirming.

Next time, please keep the CC list intact when replying so that everyone
sees that you've tested it.

Johan

Re: [PATCH] net: hso: fix NULL-deref on disconnect regression

[Greg Kroah-Hartman]

On Mon, Apr 26, 2021 at 11:35:46AM +0200, Johan Hovold wrote:
> On Mon, Apr 26, 2021 at 11:29:11AM +0200, Leonardo Antoniazzi wrote:
> > On Mon, 26 Apr 2021 10:11:49 +0200
> > Johan Hovold <johan@kernel.org> wrote:
> > 
> > > Commit 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device
> > > unregistration") fixed the racy minor allocation reported by syzbot, but
> > > introduced an unconditional NULL-pointer dereference on every disconnect
> > > instead.
> > > 
> > > Specifically, the serial device table must no longer be accessed after
> > > the minor has been released by hso_serial_tty_unregister().
> > > 
> > > Fixes: 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device unregistration")
> > > Cc: stable@vger.kernel.org
> > > Cc: Anirudh Rayabharam <mail@anirudhrb.com>
> > > Reported-by: Leonardo Antoniazzi <leoanto@aruba.it>
> > > Signed-off-by: Johan Hovold <johan@kernel.org>
> > > ---
> 
> > the patch fix the problem
> 
> Thanks for confirming.
> 
> Next time, please keep the CC list intact when replying so that everyone
> sees that you've tested it.

Wonderful.  Johan, thanks for the quick fix.

netdev maintainers, mind if I take this fix through my tree to Linus
this week, or can you all get it to him before -rc1 through the
networking tree?

thanks,

greg k-h

Re: [PATCH] net: hso: fix NULL-deref on disconnect regression

[David Miller]

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Mon, 26 Apr 2021 11:50:44 +0200

> netdev maintainers, mind if I take this fix through my tree to Linus
> this week, or can you all get it to him before -rc1 through the
> networking tree?

I tossed this into net-next so Linus will see it later this week.

Thanks.

Re: [PATCH] net: hso: fix NULL-deref on disconnect regression

[Greg KH]

On Mon, Apr 26, 2021 at 01:09:19PM -0700, David Miller wrote:
> From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Date: Mon, 26 Apr 2021 11:50:44 +0200
> 
> > netdev maintainers, mind if I take this fix through my tree to Linus
> > this week, or can you all get it to him before -rc1 through the
> > networking tree?
> 
> I tossed this into net-next so Linus will see it later this week.

Wonderful, thanks!

greg k-h

Re: [PATCH] net: hso: fix NULL-deref on disconnect regression

[Anirudh Rayabharam]

On Mon, Apr 26, 2021 at 10:11:49AM +0200, Johan Hovold wrote:
> Commit 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device
> unregistration") fixed the racy minor allocation reported by syzbot, but
> introduced an unconditional NULL-pointer dereference on every disconnect
> instead.
> 
> Specifically, the serial device table must no longer be accessed after
> the minor has been released by hso_serial_tty_unregister().
> 
> Fixes: 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device unregistration")
> Cc: stable@vger.kernel.org
> Cc: Anirudh Rayabharam <mail@anirudhrb.com>
> Reported-by: Leonardo Antoniazzi <leoanto@aruba.it>
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
>  drivers/net/usb/hso.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
> index 9bc58e64b5b7..3ef4b2841402 100644
> --- a/drivers/net/usb/hso.c
> +++ b/drivers/net/usb/hso.c
> @@ -3104,7 +3104,7 @@ static void hso_free_interface(struct usb_interface *interface)
>  			cancel_work_sync(&serial_table[i]->async_put_intf);
>  			cancel_work_sync(&serial_table[i]->async_get_intf);
>  			hso_serial_tty_unregister(serial);
> -			kref_put(&serial_table[i]->ref, hso_serial_ref_free);
> +			kref_put(&serial->parent->ref, hso_serial_ref_free);
>  		}
>  	}

Ah, my bad. Thanks Johan for the fix!

Reviewed-by: Anirudh Rayabharam <mail@anirudhrb.com>

	- Anirudh.

Re: [PATCH] net: hso: fix NULL-deref on disconnect regression

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Mon, 26 Apr 2021 10:11:49 +0200 you wrote:
> Commit 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device
> unregistration") fixed the racy minor allocation reported by syzbot, but
> introduced an unconditional NULL-pointer dereference on every disconnect
> instead.
> 
> Specifically, the serial device table must no longer be accessed after
> the minor has been released by hso_serial_tty_unregister().
> 
> [...]

Here is the summary with links:
  - net: hso: fix NULL-deref on disconnect regression
    https://git.kernel.org/netdev/net-next/c/2ad5692db728

You are awesome, thank you!
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