NFC: st21nfca: Fix memory leak in device probe and remove

'phy->pending_skb' is alloced when device probe, but forgot to free
in the error handling path and remove path, this cause memory leak
as follows:

unreferenced object 0xffff88800bc06800 (size 512):
  comm "8", pid 11775, jiffies 4295159829 (age 9.032s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000d66c09ce>] __kmalloc_node_track_caller+0x1ed/0x450
    [<00000000c93382b3>] kmalloc_reserve+0x37/0xd0
    [<000000005fea522c>] __alloc_skb+0x124/0x380
    [<0000000019f29f9a>] st21nfca_hci_i2c_probe+0x170/0x8f2

Fix it by freeing 'pending_skb' in error and remove.

Fixes: 68957303 ("NFC: ST21NFCA: Add driver for STMicroelectronics ST21NFCA NFC Chip")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/nfc/st21nfca/i2c.c

@@ -524,7 +524,8 @@ static int st21nfca_hci_i2c_probe(struct i2c_client *client,
 	phy->gpiod_ena = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
 	if (IS_ERR(phy->gpiod_ena)) {
 		nfc_err(dev, "Unable to get ENABLE GPIO\n");
-		return PTR_ERR(phy->gpiod_ena);
+		r = PTR_ERR(phy->gpiod_ena);
+		goto out_free;
 	}
 
 	phy->se_status.is_ese_present =
@@ -535,7 +536,7 @@ static int st21nfca_hci_i2c_probe(struct i2c_client *client,
 	r = st21nfca_hci_platform_init(phy);
 	if (r < 0) {
 		nfc_err(&client->dev, "Unable to reboot st21nfca\n");
-		return r;
+		goto out_free;
 	}
 
 	r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
@@ -544,15 +545,23 @@ static int st21nfca_hci_i2c_probe(struct i2c_client *client,
 				ST21NFCA_HCI_DRIVER_NAME, phy);
 	if (r < 0) {
 		nfc_err(&client->dev, "Unable to register IRQ handler\n");
-		return r;
+		goto out_free;
 	}
 
-	return st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
+	r = st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
 			       ST21NFCA_FRAME_HEADROOM,
 			       ST21NFCA_FRAME_TAILROOM,
 			       ST21NFCA_HCI_LLC_MAX_PAYLOAD,
 			       &phy->hdev,
 			       &phy->se_status);
+	if (r)
+		goto out_free;
+
+	return 0;
+
+out_free:
+	kfree_skb(phy->pending_skb);
+	return r;
 }
 
 static int st21nfca_hci_i2c_remove(struct i2c_client *client)
@@ -563,6 +572,8 @@ static int st21nfca_hci_i2c_remove(struct i2c_client *client)
 
 	if (phy->powered)
 		st21nfca_hci_i2c_disable(phy);
+	if (phy->pending_skb)
+		kfree_skb(phy->pending_skb);
 
 	return 0;
 }