NFC: st21nfcb: Fix "NULL pointer dereference" possible error

When the platform with CONFIG_ST21NFCB_I2C=y without any st21nfcb component
physically connected a:
"Unable to handle kernel NULL pointer dereference at virtual address" may
show up at driver initialization phase.

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 11 insertions, 7 deletions

diff --git a/drivers/nfc/st21nfcb/i2c.c b/drivers/nfc/st21nfcb/i2c.c
index b65847c62631..eb886932d972 100644
--- a/drivers/nfc/st21nfcb/i2c.c
+++ b/drivers/nfc/st21nfcb/i2c.c
@@ -199,7 +199,7 @@ static irqreturn_t st21nfcb_nci_irq_thread_fn(int irq, void *phy_id)
         struct sk_buff *skb = NULL;
         int r;
 
-        if (!phy || irq != phy->i2c_dev->irq) {
+        if (!phy || !phy->ndlc || irq != phy->i2c_dev->irq) {
                 WARN_ON_ONCE(1);
                 return IRQ_NONE;
         }
@@ -343,18 +343,22 @@ static int st21nfcb_nci_i2c_probe(struct i2c_client *client,
                 return -ENODEV;
         }
 
+        r = ndlc_probe(phy, &i2c_phy_ops, &client->dev,
+                        ST21NFCB_FRAME_HEADROOM, ST21NFCB_FRAME_TAILROOM,
+                        &phy->ndlc);
+        if (r < 0) {
+                nfc_err(&client->dev, "Unable to register ndlc layer\n");
+                return r;
+        }
+
         r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
                                 st21nfcb_nci_irq_thread_fn,
                                 phy->irq_polarity | IRQF_ONESHOT,
                                 ST21NFCB_NCI_DRIVER_NAME, phy);
-        if (r < 0) {
+        if (r < 0)
                 nfc_err(&client->dev, "Unable to register IRQ handler\n");
-                return r;
-        }
 
-        return ndlc_probe(phy, &i2c_phy_ops, &client->dev,
-                        ST21NFCB_FRAME_HEADROOM, ST21NFCB_FRAME_TAILROOM,
-                        &phy->ndlc);
+        return r;
 }
 
 static int st21nfcb_nci_i2c_remove(struct i2c_client *client)