[patch]race between disconnect and open in usbtouchscreen

[patch]race between disconnect and open in usbtouchscreen

[Oliver Neukum]

Hi,

an open() between killing the urb and unregistering the device
can lead to IO to a disconnected device.

	Regards
		Oliver

Signed-off-by: Oliver Neukum <oliver-GvhC2dPhHPQdnm+yROfE0A@public.gmane.org>

--

commit e15f9b41115356ca5399f77bbc6b364c41b7f780
Author: Oliver Neukum <oliver-GvhC2dPhHPQdnm+yROfE0A@public.gmane.org>
Date:   Fri Nov 20 21:50:38 2009 +0100

    usbtouchscreen: fix race between open and disconnect
    
    the input device must be unregistered before IO is stopped
    so that open cannot restart IO

diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
index 68ece58..6850b0d 100644
--- a/drivers/input/touchscreen/usbtouchscreen.c
+++ b/drivers/input/touchscreen/usbtouchscreen.c
@@ -1087,8 +1087,8 @@ static void usbtouch_disconnect(struct usb_interface *intf)
 
 	dbg("%s - usbtouch is initialized, cleaning up", __func__);
 	usb_set_intfdata(intf, NULL);
-	usb_kill_urb(usbtouch->irq);
 	input_unregister_device(usbtouch->input);
+	usb_kill_urb(usbtouch->irq);
 	usb_free_urb(usbtouch->irq);
 	usbtouch_free_buffers(interface_to_usbdev(intf), usbtouch);
 	kfree(usbtouch);

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Re: [patch]race between disconnect and open in usbtouchscreen

[Dmitry Torokhov]

Hi Oliver,

On Fri, Nov 20, 2009 at 10:13:47PM +0100, Oliver Neukum wrote:
> Hi,
> 
> an open() between killing the urb and unregistering the device
> can lead to IO to a disconnected device.
> 

usbtouch_close() calls usb_kill_urb() so there is no race.
usb_kill_urb() simply not needed in usbtouch_disconnect().

Thanks.

-- 
Dmitry

Re: [patch]race between disconnect and open in usbtouchscreen

[Oliver Neukum]

Am Freitag, 20. November 2009 22:22:59 schrieb Dmitry Torokhov:
> Hi Oliver,
> 
> On Fri, Nov 20, 2009 at 10:13:47PM +0100, Oliver Neukum wrote:
> > Hi,
> >
> > an open() between killing the urb and unregistering the device
> > can lead to IO to a disconnected device.
> 
> usbtouch_close() calls usb_kill_urb() so there is no race.
> usb_kill_urb() simply not needed in usbtouch_disconnect().

Then it needs to go.

Signed-off-by: Oliver Neukum <oliver@neukum.org>

	Regards
		Oliver

--

commit 2705666144b8c898283974efc59fd5182e13e652
Author: Oliver Neukum <oliver@neukum.org>
Date:   Fri Nov 20 22:41:04 2009 +0100

    usbtouchscreen:remove unneeded usb_kill_urb
    
    usb_kill_urb() in disconnect is not needed as unregistering
    cause close to be called

diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
index 68ece58..eddb628 100644
--- a/drivers/input/touchscreen/usbtouchscreen.c
+++ b/drivers/input/touchscreen/usbtouchscreen.c
@@ -1087,7 +1087,7 @@ static void usbtouch_disconnect(struct usb_interface *intf)
 
 	dbg("%s - usbtouch is initialized, cleaning up", __func__);
 	usb_set_intfdata(intf, NULL);
-	usb_kill_urb(usbtouch->irq);
+	/* this will stop IO via close */
 	input_unregister_device(usbtouch->input);
 	usb_free_urb(usbtouch->irq);
 	usbtouch_free_buffers(interface_to_usbdev(intf), usbtouch);

Re: [patch]race between disconnect and open in usbtouchscreen

[Dmitry Torokhov]

On Fri, Nov 20, 2009 at 10:49:56PM +0100, Oliver Neukum wrote:
> Am Freitag, 20. November 2009 22:22:59 schrieb Dmitry Torokhov:
> > Hi Oliver,
> > 
> > On Fri, Nov 20, 2009 at 10:13:47PM +0100, Oliver Neukum wrote:
> > > Hi,
> > >
> > > an open() between killing the urb and unregistering the device
> > > can lead to IO to a disconnected device.
> > 
> > usbtouch_close() calls usb_kill_urb() so there is no race.
> > usb_kill_urb() simply not needed in usbtouch_disconnect().
> 
> Then it needs to go.
> 

Applied, thank you Oliver.

-- 
Dmitry