[PATCH] usb: roles: fix a potential use after free

[PATCH] usb: roles: fix a potential use after free

[Wen Yang]

Free the sw structure only after we are done using it.
This patch just moves the put_device() down a bit to avoid the
use after free.

Fixes: 5c54fcac9a9d ("usb: roles: Take care of driver module reference counting")
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/usb/roles/class.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
index 8273126..63a00ff 100644
--- a/drivers/usb/roles/class.c
+++ b/drivers/usb/roles/class.c
@@ -169,8 +169,8 @@ struct usb_role_switch *fwnode_usb_role_switch_get(struct fwnode_handle *fwnode)
 void usb_role_switch_put(struct usb_role_switch *sw)
 {
 	if (!IS_ERR_OR_NULL(sw)) {
-		put_device(&sw->dev);
 		module_put(sw->dev.parent->driver->owner);
+		put_device(&sw->dev);
 	}
 }
 EXPORT_SYMBOL_GPL(usb_role_switch_put);
-- 
1.8.3.1

Re: [PATCH] usb: roles: fix a potential use after free

[Peter Chen]

On 19-11-24 22:22:36, Wen Yang wrote:
> Free the sw structure only after we are done using it.
> This patch just moves the put_device() down a bit to avoid the
> use after free.
> 
> Fixes: 5c54fcac9a9d ("usb: roles: Take care of driver module reference counting")
> Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: linux-usb@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  drivers/usb/roles/class.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
> index 8273126..63a00ff 100644
> --- a/drivers/usb/roles/class.c
> +++ b/drivers/usb/roles/class.c
> @@ -169,8 +169,8 @@ struct usb_role_switch *fwnode_usb_role_switch_get(struct fwnode_handle *fwnode)
>  void usb_role_switch_put(struct usb_role_switch *sw)
>  {
>  	if (!IS_ERR_OR_NULL(sw)) {
> -		put_device(&sw->dev);
>  		module_put(sw->dev.parent->driver->owner);
> +		put_device(&sw->dev);
>  	}
>  }
>  EXPORT_SYMBOL_GPL(usb_role_switch_put);
> -- 
> 1.8.3.1
> 

Reviewed-by: Peter Chen <peter.chen@nxp.com>

-- 

Thanks,
Peter Chen

Re: [PATCH] usb: roles: fix a potential use after free

[Heikki Krogerus]

On Sun, Nov 24, 2019 at 10:22:36PM +0800, Wen Yang wrote:
> Free the sw structure only after we are done using it.
> This patch just moves the put_device() down a bit to avoid the
> use after free.
> 
> Fixes: 5c54fcac9a9d ("usb: roles: Take care of driver module reference counting")
> Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: linux-usb@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  drivers/usb/roles/class.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
> index 8273126..63a00ff 100644
> --- a/drivers/usb/roles/class.c
> +++ b/drivers/usb/roles/class.c
> @@ -169,8 +169,8 @@ struct usb_role_switch *fwnode_usb_role_switch_get(struct fwnode_handle *fwnode)
>  void usb_role_switch_put(struct usb_role_switch *sw)
>  {
>  	if (!IS_ERR_OR_NULL(sw)) {
> -		put_device(&sw->dev);
>  		module_put(sw->dev.parent->driver->owner);
> +		put_device(&sw->dev);
>  	}
>  }
>  EXPORT_SYMBOL_GPL(usb_role_switch_put);
> -- 
> 1.8.3.1

-- 
heikki

Re: [PATCH] usb: roles: fix a potential use after free

[Heikki Krogerus]

On Tue, Nov 26, 2019 at 05:49:17PM +0200, Heikki Krogerus wrote:
> On Sun, Nov 24, 2019 at 10:22:36PM +0800, Wen Yang wrote:
> > Free the sw structure only after we are done using it.
> > This patch just moves the put_device() down a bit to avoid the
> > use after free.
> > 
> > Fixes: 5c54fcac9a9d ("usb: roles: Take care of driver module reference counting")
> > Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
> > Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > Cc: Hans de Goede <hdegoede@redhat.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
> > Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> > Cc: linux-usb@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org

Ups, sorry. I meant:

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

thanks,

-- 
heikki