[PATCH v3 net] can: sja1000: fix use after free in ems_pcmcia_add_card()

If the last channel is not available then "dev" is freed.  Fortunately,
we can just use "pdev->irq" instead.

Also we should check if at least one channel was set up.

Fixes: fd734c6f25ae ("can/sja1000: add driver for EMS PCMCIA card")
Signed-off-by: Dan Carpenter <redacted>
---
v3: add a check for if there is a channel.
v2: fix a bug in v1.  Only one channel is required but my patch returned
    if any channel was unavailable.

 drivers/net/can/sja1000/ems_pcmcia.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/sja1000/ems_pcmcia.c b/drivers/net/can/sja1000/ems_pcmcia.c
index e21b169c14c0..4642b6d4aaf7 100644
--- a/drivers/net/can/sja1000/ems_pcmcia.c
+++ b/drivers/net/can/sja1000/ems_pcmcia.c

@@ -234,7 +234,12 @@ static int ems_pcmcia_add_card(struct pcmcia_device *pdev, unsigned long base)
 			free_sja1000dev(dev);
 	}
 
-	err = request_irq(dev->irq, &ems_pcmcia_interrupt, IRQF_SHARED,
+	if (!card->channels) {
+		err = -ENODEV;
+		goto failure_cleanup;
+	}
+
+	err = request_irq(pdev->irq, &ems_pcmcia_interrupt, IRQF_SHARED,
 			  DRV_NAME, card);
 	if (!err)
 		return 0;

-- 
2.20.1

On 24.11.21 15:50, Dan Carpenter wrote:

If the last channel is not available then "dev" is freed.  Fortunately,
we can just use "pdev->irq" instead.

Also we should check if at least one channel was set up.

Fixes: fd734c6f25ae ("can/sja1000: add driver for EMS PCMCIA card")
Signed-off-by: Dan Carpenter <redacted>

Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Tested-by: Oliver Hartkopp <socketcan@hartkopp.net>

Thanks Dan!