* [bug report] NFC: fix broken device allocation
@ 2017-07-07 9:33 Dan Carpenter
2017-07-07 18:32 ` Johan Hovold
0 siblings, 1 reply; 2+ messages in thread
From: Dan Carpenter @ 2017-07-07 9:33 UTC (permalink / raw)
To: johan; +Cc: linux-wireless
Hello Johan Hovold,
The patch 20777bc57c34: "NFC: fix broken device allocation" from Mar
30, 2017, leads to the following static checker warning:
drivers/nfc/pn533/pn533.c:2653 pn533_register_device()
error: 'priv->nfc_dev' dereferencing possible ERR_PTR()
drivers/nfc/pn533/pn533.c
2639 skb_queue_head_init(&priv->resp_q);
2640 skb_queue_head_init(&priv->fragment_skb);
2641
2642 INIT_LIST_HEAD(&priv->cmd_queue);
2643
2644 priv->nfc_dev = nfc_allocate_device(&pn533_nfc_ops, protocols,
2645 priv->ops->tx_header_len +
2646 PN533_CMD_DATAEXCH_HEAD_LEN,
2647 priv->ops->tx_tail_len);
We changed this to return error pointers as well as NULL. When
functions return a NULL as well as error pointers, then NULL is supposed
to be a special case of success but here it's just a failure. That's
messy and bug prone.
2648 if (!priv->nfc_dev) {
2649 rc = -ENOMEM;
2650 goto destroy_wq;
2651 }
2652
2653 nfc_set_parent_dev(priv->nfc_dev, parent);
^^^^^^^^^^^^^
Oops.
2654 nfc_set_drvdata(priv->nfc_dev, priv);
2655
2656 rc = nfc_register_device(priv->nfc_dev);
2657 if (rc)
2658 goto free_nfc_dev;
regards,
dan carpenter
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [bug report] NFC: fix broken device allocation
2017-07-07 9:33 [bug report] NFC: fix broken device allocation Dan Carpenter
@ 2017-07-07 18:32 ` Johan Hovold
0 siblings, 0 replies; 2+ messages in thread
From: Johan Hovold @ 2017-07-07 18:32 UTC (permalink / raw)
To: Dan Carpenter; +Cc: johan, linux-wireless
On Fri, Jul 07, 2017 at 12:33:34PM +0300, Dan Carpenter wrote:
> Hello Johan Hovold,
>
> The patch 20777bc57c34: "NFC: fix broken device allocation" from Mar
> 30, 2017, leads to the following static checker warning:
>
> drivers/nfc/pn533/pn533.c:2653 pn533_register_device()
> error: 'priv->nfc_dev' dereferencing possible ERR_PTR()
> drivers/nfc/pn533/pn533.c
> 2639 skb_queue_head_init(&priv->resp_q);
> 2640 skb_queue_head_init(&priv->fragment_skb);
> 2641
> 2642 INIT_LIST_HEAD(&priv->cmd_queue);
> 2643
> 2644 priv->nfc_dev = nfc_allocate_device(&pn533_nfc_ops, protocols,
> 2645 priv->ops->tx_header_len +
> 2646 PN533_CMD_DATAEXCH_HEAD_LEN,
> 2647 priv->ops->tx_tail_len);
>
> We changed this to return error pointers as well as NULL. When
> functions return a NULL as well as error pointers, then NULL is supposed
> to be a special case of success but here it's just a failure. That's
> messy and bug prone.
Thanks for reporting this, Dan.
I'll take a closer look at this tomorrow, but I guess we could just
continue using NULL for all errors for now.
Thanks,
Johan
^ permalink raw reply [flat|nested] 2+ messages in thread
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