[PATCH v2 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.

Fixes: fd734c6f25ae ("can/sja1000: add driver for EMS PCMCIA card")
Signed-off-by: Dan Carpenter <redacted>
---
v2: In the first version, I just failed the probe.  Sorry about that.

 drivers/net/can/sja1000/ems_pcmcia.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/sja1000/ems_pcmcia.c b/drivers/net/can/sja1000/ems_pcmcia.c
index e21b169c14c0..391a8253ed6f 100644
--- a/drivers/net/can/sja1000/ems_pcmcia.c
+++ b/drivers/net/can/sja1000/ems_pcmcia.c

@@ -234,7 +234,7 @@ 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,
+	err = request_irq(pdev->irq, &ems_pcmcia_interrupt, IRQF_SHARED,
 			  DRV_NAME, card);
 	if (!err)
 		return 0;

-- 
2.20.1

Hello Dan,

On 24.11.21 07:56, Dan Carpenter wrote:

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

But in the case that we do not find any channel the irq for the card is 
still requested (via pdev->irq).

When adding this check, we should be fine:

+	if (card->channels)

+	err = request_irq(pdev->irq, &ems_pcmcia_interrupt, IRQF_SHARED,
  			  DRV_NAME, card);
  	if (!err)
  		return 0;

Thanks for checking this code after so many years!

I saved that 17 year old EMS PCMCIA Card from my former CAN hardware box 
two weeks ago and made a 5.16-rc2 run on a 2006 Samsung X20 with Pentium 
M 1.7GHz yesterday. My only machine here at home with a PCMCIA slot :-D

https://www.amazon.de/Samsung-Centrino-1-73GHz-Graphic-Accelerator/dp/B000AXSIRE

And it still works with the CAN card!

Best regards,
Oliver

On Wed, Nov 24, 2021 at 08:37:27AM +0100, Oliver Hartkopp wrote:

Hello Dan,

On 24.11.21 07:56, Dan Carpenter wrote:

quoted

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

But in the case that we do not find any channel the irq for the card is
still requested (via pdev->irq).

quoted

Fixes: fd734c6f25ae ("can/sja1000: add driver for EMS PCMCIA card")
Signed-off-by: Dan Carpenter <redacted>
---
v2: In the first version, I just failed the probe.  Sorry about that.

  drivers/net/can/sja1000/ems_pcmcia.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/sja1000/ems_pcmcia.c b/drivers/net/can/sja1000/ems_pcmcia.c
index e21b169c14c0..391a8253ed6f 100644
--- a/drivers/net/can/sja1000/ems_pcmcia.c
+++ b/drivers/net/can/sja1000/ems_pcmcia.c

@@ -234,7 +234,7 @@ 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,

When adding this check, we should be fine:

+	if (card->channels)

Sure,  I will send a v3 with that.

regards,
dan carpenter

On 24.11.21 09:57, Dan Carpenter wrote:

On Wed, Nov 24, 2021 at 08:37:27AM +0100, Oliver Hartkopp wrote:

quoted

Hello Dan,

On 24.11.21 07:56, Dan Carpenter wrote:

quoted

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

But in the case that we do not find any channel the irq for the card is
still requested (via pdev->irq).

quoted

Fixes: fd734c6f25ae ("can/sja1000: add driver for EMS PCMCIA card")
Signed-off-by: Dan Carpenter <redacted>
---
v2: In the first version, I just failed the probe.  Sorry about that.

   drivers/net/can/sja1000/ems_pcmcia.c | 2 +-
   1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/sja1000/ems_pcmcia.c b/drivers/net/can/sja1000/ems_pcmcia.c
index e21b169c14c0..391a8253ed6f 100644
--- a/drivers/net/can/sja1000/ems_pcmcia.c
+++ b/drivers/net/can/sja1000/ems_pcmcia.c

@@ -234,7 +234,7 @@ 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,

When adding this check, we should be fine:

+	if (card->channels)

Sure,  I will send a v3 with that.

With these discussed changes you might directly add my

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

Thanks,
Oliver