[PATCH] nfc: fdp: fix NULL pointer dereference

[PATCH] nfc: fdp: fix NULL pointer dereference

[Sudip Mukherjee]

We are checking phy after dereferencing it. We can print the debug
information after checking it. If phy is NULL then we will get a good
stack trace to tell us that we are in this irq handler.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
---
 drivers/nfc/fdp/i2c.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/nfc/fdp/i2c.c b/drivers/nfc/fdp/i2c.c
index 5e797d5..712936f 100644
--- a/drivers/nfc/fdp/i2c.c
+++ b/drivers/nfc/fdp/i2c.c
@@ -210,14 +210,14 @@ static irqreturn_t fdp_nci_i2c_irq_thread_fn(int irq, void *phy_id)
 	struct sk_buff *skb;
 	int r;
 
-	client = phy->i2c_dev;
-	dev_dbg(&client->dev, "%s\n", __func__);
-
 	if (!phy || irq != phy->i2c_dev->irq) {
 		WARN_ON_ONCE(1);
 		return IRQ_NONE;
 	}
 
+	client = phy->i2c_dev;
+	dev_dbg(&client->dev, "%s\n", __func__);
+
 	r = fdp_nci_i2c_read(phy, &skb);
 
 	if (r == -EREMOTEIO)
-- 
1.9.1

Re: [PATCH] nfc: fdp: fix NULL pointer dereference

[Samuel Ortiz]

Hi Sudip,

On Tue, Dec 20, 2016 at 09:09:04PM +0000, Sudip Mukherjee wrote:
> We are checking phy after dereferencing it. We can print the debug
> information after checking it. If phy is NULL then we will get a good
> stack trace to tell us that we are in this irq handler.
> 
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
> ---
>  drivers/nfc/fdp/i2c.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
Applied to nfc-next, thanks.

Cheers,
Samuel.