Re: [PATCH v1] usb: cdns3: cdns3-gadget: fix use-after-free bug in cdns3_gadget_exit due to race

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, May 13, 2024 at 10:19:48AM +0800, Sicong Huang wrote:
> This bug exists in drivers/usb/cdns3/cdns3-gadget.c. Function
> __cdns3_gadget_init will call cdns3_gadget_start to do futher jobs
> during the initialization proccess of cdns3 gadget. In cdns3_gadget_start,
> &priv_dev->pending_status_wq is bound with cdns3_pending_setup_status_handler.
> Then this work will be added to system_freezable_wq in cdns3_gadget_ep0_queue.
> Here is the code.
> queue_work(system_freezable_wq, &priv_dev->pending_status_wq);
> 
> If we call cdns3_gadget_exit to remove the device and make cleanup,
> there are some unfinished works. This function will call cdns3_free_all_eps to
> free all the endpoints. However, if cdns3_pending_setup_status_handler is
> scheduled to run after the free job, it will cause use-after-free error as
> cdns3_pending_setup_status_handler will use the endpoint in the following code.
> request->complete(&priv_dev->eps[0]->endpoint, request);
> 
> The possible execution flow that may lead to this issue is as follows:
> CPU0                    CPU1
>                       | __cdns3_gadget_init
>                       | cdns3_gadget_start
> cdns3_gadget_exit     |
> cdns3_free_all_eps    |
> devm_kfree (free)     |
>                       | cdns3_pending_setup_status_handler
>                       | &priv_dev->eps[0]->endpoint (use)
> 
> Fix it by cleaning the work in cdns3_gadget_exit.
> 
> Signed-off-by: Sicong Huang <congei42@163.com>
> ---
>  drivers/usb/cdns3/cdns3-gadget.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
> index fd1beb10bba7..0f2e143bd17a 100644
> --- a/drivers/usb/cdns3/cdns3-gadget.c
> +++ b/drivers/usb/cdns3/cdns3-gadget.c
> @@ -3252,6 +3252,9 @@ static void cdns3_gadget_exit(struct cdns *cdns)
>  	pm_runtime_mark_last_busy(cdns->dev);
>  	pm_runtime_put_autosuspend(cdns->dev);
>  
> +	cancel_work_sync(&priv_dev->pending_status_wq);
> +	cancel_work_sync(&priv_dev->aligned_buf_wq);
> +
>  	usb_del_gadget(&priv_dev->gadget);
>  	devm_free_irq(cdns->dev, cdns->dev_irq, priv_dev);
>  
> -- 
> 2.34.1

What commit id does this fix?

thanks,

greg k-h