In the original code if ems_pcmcia_check_chan() returned false then it called free_sja1000dev(dev) but did not set the error code or jump to the clean up code. This frees "dev" and leads to a use after free. I flipped the ems_pcmcia_check_chan() check around to make the error handling more consistent and readable. That lets us pull the rest of the code in one tab. Fixes: fd734c6f25ae ("can/sja1000: add driver for EMS PCMCIA card") Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> --- drivers/net/can/sja1000/ems_pcmcia.c | 44 +++++++++++++++------------- 1 file changed, 23 insertions(+), 21 deletions(-) diff --git a/drivers/net/can/sja1000/ems_pcmcia.c b/drivers/net/can/sja1000/ems_pcmcia.c index e21b169c14c0..271fe9444827 100644 --- a/drivers/net/can/sja1000/ems_pcmcia.c +++ b/drivers/net/can/sja1000/ems_pcmcia.c @@ -210,28 +210,30 @@ static int ems_pcmcia_add_card(struct pcmcia_device *pdev, unsigned long base) (i * EMS_PCMCIA_CAN_CTRL_SIZE); /* Check if channel is present */ - if (ems_pcmcia_check_chan(priv)) { - priv->read_reg = ems_pcmcia_read_reg; - priv->write_reg = ems_pcmcia_write_reg; - priv->can.clock.freq = EMS_PCMCIA_CAN_CLOCK; - priv->ocr = EMS_PCMCIA_OCR; - priv->cdr = EMS_PCMCIA_CDR; - priv->flags |= SJA1000_CUSTOM_IRQ_HANDLER; - - /* Register SJA1000 device */ - err = register_sja1000dev(dev); - if (err) { - free_sja1000dev(dev); - goto failure_cleanup; - } - - card->channels++; - - printk(KERN_INFO "%s: registered %s on channel " - "#%d at 0x%p, irq %d\n", DRV_NAME, dev->name, - i, priv->reg_base, dev->irq); - } else + if (!ems_pcmcia_check_chan(priv)) { + err = -EINVAL; free_sja1000dev(dev); + goto failure_cleanup; + } + priv->read_reg = ems_pcmcia_read_reg; + priv->write_reg = ems_pcmcia_write_reg; + priv->can.clock.freq = EMS_PCMCIA_CAN_CLOCK; + priv->ocr = EMS_PCMCIA_OCR; + priv->cdr = EMS_PCMCIA_CDR; + priv->flags |= SJA1000_CUSTOM_IRQ_HANDLER; + + /* Register SJA1000 device */ + err = register_sja1000dev(dev); + if (err) { + free_sja1000dev(dev); + goto failure_cleanup; + } + + card->channels++; + + printk(KERN_INFO "%s: registered %s on channel " + "#%d at 0x%p, irq %d\n", DRV_NAME, dev->name, + i, priv->reg_base, dev->irq); } err = request_irq(dev->irq, &ems_pcmcia_interrupt, IRQF_SHARED, -- 2.20.1