[PATCH net v3] ice: Add check for kzalloc

[Jiasheng Jiang <jiasheng@iscas.ac.cn>]

As kzalloc may return NULL pointer, the return value should
be checked and return error if fails in order to avoid the
NULL pointer dereference.
Moreover, use the goto-label to share the clean code.

Fixes: d6b98c8d242a ("ice: add write functionality for GNSS TTY")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
Changelog:

v2 -> v3:

1. Use "while (i--)" to simplify the code.

v1 -> v2:

1. Use goto-label to share the clean code.
---
 drivers/net/ethernet/intel/ice/ice_gnss.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_gnss.c b/drivers/net/ethernet/intel/ice/ice_gnss.c
index b5a7f246d230..90c620c26516 100644
--- a/drivers/net/ethernet/intel/ice/ice_gnss.c
+++ b/drivers/net/ethernet/intel/ice/ice_gnss.c
@@ -462,6 +462,9 @@ static struct tty_driver *ice_gnss_create_tty_driver(struct ice_pf *pf)
 					       GFP_KERNEL);
 		pf->gnss_serial[i] = NULL;
 
+		if (!pf->gnss_tty_port[i])
+			goto err_out;
+
 		tty_port_init(pf->gnss_tty_port[i]);
 		tty_port_link_device(pf->gnss_tty_port[i], tty_driver, i);
 	}
@@ -469,21 +472,23 @@ static struct tty_driver *ice_gnss_create_tty_driver(struct ice_pf *pf)
 	err = tty_register_driver(tty_driver);
 	if (err) {
 		dev_err(dev, "Failed to register TTY driver err=%d\n", err);
-
-		for (i = 0; i < ICE_GNSS_TTY_MINOR_DEVICES; i++) {
-			tty_port_destroy(pf->gnss_tty_port[i]);
-			kfree(pf->gnss_tty_port[i]);
-		}
-		kfree(ttydrv_name);
-		tty_driver_kref_put(pf->ice_gnss_tty_driver);
-
-		return NULL;
+		goto err_out;
 	}
 
 	for (i = 0; i < ICE_GNSS_TTY_MINOR_DEVICES; i++)
 		dev_info(dev, "%s%d registered\n", ttydrv_name, i);
 
 	return tty_driver;
+
+err_out:
+	while (i--) {
+		tty_port_destroy(pf->gnss_tty_port[i]);
+		kfree(pf->gnss_tty_port[i]);
+	}
+	kfree(ttydrv_name);
+	tty_driver_kref_put(pf->ice_gnss_tty_driver);
+
+	return NULL;
 }
 
 /**
-- 
2.25.1