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

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Message-ID: <CAGrhNMyF=QpXnw6FZp=_2s=_4Du+gOFGTzWwfBYctwkBO3szaQ@mail.gmail.com>
Date:	Fri, 18 Sep 2015 18:30:52 +0100
From:	Felipe Tonello <eu@...ipetonello.com>
To:	Felipe Balbi <balbi@...com>
Cc:	USB list <linux-usb@...r.kernel.org>, linux-kernel@...r.kernel.org,
	Peter Chen <Peter.Chen@...escale.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andrzej Pietrasiewicz <andrzej.p@...sung.com>
Subject: Re: [PATCH 1/2] usb: chipidea: udc: improve error handling on ep_queue

Hi Felipe,

On Fri, Sep 18, 2015 at 6:17 PM, Felipe Balbi <balbi@...com> wrote:
> 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.

Got it.

>
>>   *
>>   * 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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