netdev - [PATCH v3 net] can: sja1000: fix use after free in ems_pcmcia_add

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Date:   Wed, 24 Nov 2021 17:50:41 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Wolfgang Grandegger <wg@...ndegger.com>
Cc:     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>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [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 <dan.carpenter@...cle.com>
---
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