[PATCH] tablet: acecad: update the reference count of the usb interface structure

[PATCH] tablet: acecad: update the reference count of the usb interface structure

[Salah Triki]

Use usb_get_intf() and usb_put_intf() in order to update the reference
count of the usb interface structure.

Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
 drivers/input/tablet/acecad.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/input/tablet/acecad.c b/drivers/input/tablet/acecad.c
index a38d1fe97334..85fe134a30ee 100644
--- a/drivers/input/tablet/acecad.c
+++ b/drivers/input/tablet/acecad.c
@@ -151,7 +151,7 @@ static int usb_acecad_probe(struct usb_interface *intf, const struct usb_device_
 		goto fail2;
 	}
 
-	acecad->intf = intf;
+	acecad->intf = usb_get_intf(intf);
 	acecad->input = input_dev;
 
 	if (dev->manufacturer)
@@ -236,6 +236,9 @@ static void usb_acecad_disconnect(struct usb_interface *intf)
 	input_unregister_device(acecad->input);
 	usb_free_urb(acecad->irq);
 	usb_free_coherent(udev, 8, acecad->data, acecad->data_dma);
+
+	usb_put_intf(acecad->intf);
+
 	kfree(acecad);
 }
 
-- 
2.25.1

Re: [PATCH] tablet: acecad: update the reference count of the usb interface structure

[Dan Carpenter]

On Sat, Jul 24, 2021 at 09:55:42PM +0100, Salah Triki wrote:
> Use usb_get_intf() and usb_put_intf() in order to update the reference
> count of the usb interface structure.
> 

This commit message doesn't say what the user visible effects are.  If
you encountered this bug at runtime then please put the stack trace in
the commit mesage.

Add a Fixes tag.

> Signed-off-by: Salah Triki <salah.triki@gmail.com>
> ---
>  drivers/input/tablet/acecad.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/input/tablet/acecad.c b/drivers/input/tablet/acecad.c
> index a38d1fe97334..85fe134a30ee 100644
> --- a/drivers/input/tablet/acecad.c
> +++ b/drivers/input/tablet/acecad.c
> @@ -151,7 +151,7 @@ static int usb_acecad_probe(struct usb_interface *intf, const struct usb_device_
>  		goto fail2;
>  	}
>  
> -	acecad->intf = intf;
> +	acecad->intf = usb_get_intf(intf);
>  	acecad->input = input_dev;
>  
>  	if (dev->manufacturer)

You need to call usb_put_intf() if input_register_device() fails.

regards,
dan carpenter

Re: [PATCH] tablet: acecad: update the reference count of the usb interface structure

[Salah Triki]

On Tue, Jul 27, 2021 at 03:37:56PM +0300, Dan Carpenter wrote:
> This commit message doesn't say what the user visible effects are.  If
> you encountered this bug at runtime then please put the stack trace in
> the commit mesage.
> 

I made this patch based on the following documentation of
usb_get_intf():

[quote]
Each live reference to a interface must be refcounted.

Drivers for USB interfaces should normally record such references 
in their probe methods, when they bind to an interface, and release them 
by calling usb_put_intf, in their disconnect methods.

[/quote]

Thanx

Re: [PATCH] tablet: acecad: update the reference count of the usb interface structure

[Dan Carpenter]

On Thu, Jul 29, 2021 at 01:54:27AM +0100, Salah Triki wrote:
> On Tue, Jul 27, 2021 at 03:37:56PM +0300, Dan Carpenter wrote:
> > This commit message doesn't say what the user visible effects are.  If
> > you encountered this bug at runtime then please put the stack trace in
> > the commit mesage.
> > 
> 
> I made this patch based on the following documentation of
> usb_get_intf():
> 
> [quote]
> Each live reference to a interface must be refcounted.
> 
> Drivers for USB interfaces should normally record such references 
> in their probe methods, when they bind to an interface, and release them 
> by calling usb_put_intf, in their disconnect methods.
> 
> [/quote]

Put that information in the commit message.  Otherwise to review this
patch then I'm trying to look through the syzbot dashboard to find the
stack trace.

regards,
dan carpenter