Re: drivers/net/can/usb/peak_usb/pcan_usb.c:523 pcan_usb_decode_error() error: we previously assumed 'cf' could be null (see line 503)

From: Marc Kleine-Budde
Date: Fri Dec 03 2021 - 10:01:54 EST

On 03.12.2021 15:58:52, Marc Kleine-Budde wrote:
> On 03.12.2021 17:09:55, Dan Carpenter wrote:
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head: 58e1100fdc5990b0cc0d4beaf2562a92e621ac7d
> > commit: c11dcee758302702a83c6e85e4c4c3d9af42d2b3 can: peak_usb: pcan_usb_decode_error(): upgrade handling of bus state changes
> > config: x86_64-randconfig-m001-20211202 (https://download.01.org/0day-ci/archive/20211202/202112021833.wABxM5UN-lkp@xxxxxxxxx/config)
> > compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> >
> > smatch warnings:
> > drivers/net/can/usb/peak_usb/pcan_usb.c:523 pcan_usb_decode_error() error: we previously assumed 'cf' could be null (see line 503)
> >
> > vim +/cf +523 drivers/net/can/usb/peak_usb/pcan_usb.c
> >
> > 46be265d338833 Stephane Grosjean 2012-03-02 450 static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
> > 46be265d338833 Stephane Grosjean 2012-03-02 451 u8 status_len)
> > 46be265d338833 Stephane Grosjean 2012-03-02 452 {
> > 46be265d338833 Stephane Grosjean 2012-03-02 453 struct sk_buff *skb;
> > 46be265d338833 Stephane Grosjean 2012-03-02 454 struct can_frame *cf;
> > c11dcee7583027 Stephane Grosjean 2021-07-15 455 enum can_state new_state = CAN_STATE_ERROR_ACTIVE;
> > 46be265d338833 Stephane Grosjean 2012-03-02 456
> > 46be265d338833 Stephane Grosjean 2012-03-02 457 /* ignore this error until 1st ts received */
> > 46be265d338833 Stephane Grosjean 2012-03-02 458 if (n == PCAN_USB_ERROR_QOVR)
> > 46be265d338833 Stephane Grosjean 2012-03-02 459 if (!mc->pdev->time_ref.tick_count)
> > 46be265d338833 Stephane Grosjean 2012-03-02 460 return 0;
> > 46be265d338833 Stephane Grosjean 2012-03-02 461
> > c11dcee7583027 Stephane Grosjean 2021-07-15 462 /* allocate an skb to store the error frame */
> > c11dcee7583027 Stephane Grosjean 2021-07-15 463 skb = alloc_can_err_skb(mc->netdev, &cf);
>
> alloc_can_err_skb() ->
> alloc_canfd_skb()

Doh! It calls alloc_can_skb()

https://elixir.bootlin.com/linux/v5.15/source/drivers/net/can/dev/skb.c#L180

Marc

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