linux-kernel - Re: [PATCH 1/2] usb: chipidea: udc: improve error handling on ep

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Date:	Fri, 18 Sep 2015 12:17:20 -0500
From:	Felipe Balbi <balbi@...com>
To:	<eu@...ipetonello.com>
CC:	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Peter Chen <Peter.Chen@...escale.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...com>,
	Andrzej Pietrasiewicz <andrzej.p@...sung.com>
Subject: Re: [PATCH 1/2] usb: chipidea: udc: improve error handling on
 ep_queue

Hi,

On Fri, Sep 18, 2015 at 06:12:40PM +0100, eu@...ipetonello.com wrote:
> From: "Felipe F. Tonello" <eu@...ipetonello.com>
> 
> _ep_queue() didn't check for errors when using add_td_to_list()
> which can fail if dma_pool_alloc fails, thus causing a kernel
> panic when lastnode->ptr is NULL.
> 
> Signed-off-by: Felipe F. Tonello <eu@...ipetonello.com>

this can still be split down further.

> ---
>  drivers/usb/chipidea/udc.c | 26 +++++++++++++++++++-------
>  1 file changed, 19 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index 764f668..7169113e 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -404,9 +404,9 @@ static inline u8 _usb_addr(struct ci_hw_ep *ep)
>  }
>  
>  /**
> - * _hardware_queue: configures a request at hardware level
> - * @gadget: gadget
> + * _hardware_enqueue: configures a request at hardware level
>   * @hwep:   endpoint
> + * @hwreq:  request

this is a cleanup and you shouldn't have a fix depending on a
cleanup. Fixes are merged during the -rc cycle, while cleanups will be
deferred to the following merge window.

>   *
>   * This function returns an error code
>   */
> @@ -435,19 +435,27 @@ static int _hardware_enqueue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
>  	if (hwreq->req.dma % PAGE_SIZE)
>  		pages--;
>  
> -	if (rest == 0)
> -		add_td_to_list(hwep, hwreq, 0);
> +	if (rest == 0) {
> +		ret = add_td_to_list(hwep, hwreq, 0);
> +		if (ret < 0)
> +			goto done;
> +	}

this is your fix.

>  
>  	while (rest > 0) {
>  		unsigned count = min(hwreq->req.length - hwreq->req.actual,
>  					(unsigned)(pages * CI_HDRC_PAGE_SIZE));
> -		add_td_to_list(hwep, hwreq, count);
> +		ret = add_td_to_list(hwep, hwreq, count);
> +		if (ret < 0)
> +			goto done;

and this

>  		rest -= count;
>  	}
>  
>  	if (hwreq->req.zero && hwreq->req.length
> -	    && (hwreq->req.length % hwep->ep.maxpacket == 0))
> -		add_td_to_list(hwep, hwreq, 0);
> +	    && (hwreq->req.length % hwep->ep.maxpacket == 0)) {
> +		ret = add_td_to_list(hwep, hwreq, 0);
> +		if (ret < 0)
> +			goto done;
> +	}
>


and this.

>  	firstnode = list_first_entry(&hwreq->tds, struct td_node, td);
>  
> @@ -750,8 +758,12 @@ static void isr_get_status_complete(struct usb_ep *ep, struct usb_request *req)
>  
>  /**
>   * _ep_queue: queues (submits) an I/O request to an endpoint
> + * @ep:        endpoint
> + * @req:       request
> + * @gfp_flags: GFP flags (not used)

cleanup

>   *
>   * Caller must hold lock
> + * This function returns an error code

somewhat pointless, but could come with the cleanup, no strong
feelings.

>   */
>  static int _ep_queue(struct usb_ep *ep, struct usb_request *req,
>  		    gfp_t __maybe_unused gfp_flags)
> -- 
> 2.1.4
> 

-- 
balbi

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