netdev - Re: [PATCH v2 net] can: sja1000: fix use after free in ems_pcmcia_add

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Date:   Wed, 24 Nov 2021 11:57:05 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Oliver Hartkopp <socketcan@...tkopp.net>
Cc:     Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Leon Romanovsky <leon@...nel.org>,
        Markus Plessing <plessing@...-wuensche.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v2 net] can: sja1000: fix use after free in
 ems_pcmcia_add_card()

On Wed, Nov 24, 2021 at 08:37:27AM +0100, Oliver Hartkopp wrote:
> 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).
> 
> > 
> > Fixes: fd734c6f25ae ("can/sja1000: add driver for EMS PCMCIA card")
> > Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> > ---
> > 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