[Intel-wired-lan] [PATCH iwl-net v2] i40e: Fix potential invalid access when MAC list is empty

[Zhen Ni]

list_first_entry() never returns NULL — if the list is empty, it still
returns a pointer to an invalid object, leading to potential invalid
memory access when dereferenced.

Fix this by using list_first_entry_or_null instead of list_first_entry.

Fixes: e3219ce6a775 ("i40e: Add support for client interface for IWARP driver")
Signed-off-by: Zhen Ni <zhen...@easystack.cn>
---
Changes in v2:
- Replace the list_empty() pre-check with list_first_entry_or_null()
---
 drivers/net/ethernet/intel/i40e/i40e_client.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_client.c 
b/drivers/net/ethernet/intel/i40e/i40e_client.c
index 5f1a405cbbf8..518bc738ea3b 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_client.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_client.c
@@ -359,8 +359,8 @@ static void i40e_client_add_instance(struct i40e_pf *pf)
        if (i40e_client_get_params(vsi, &cdev->lan_info.params))
                goto free_cdev;
 
-       mac = list_first_entry(&cdev->lan_info.netdev->dev_addrs.list,
-                              struct netdev_hw_addr, list);
+       mac = list_first_entry_or_null(&cdev->lan_info.netdev->dev_addrs.list,
+                                      struct netdev_hw_addr, list);
        if (mac)
                ether_addr_copy(cdev->lan_info.lanmac, mac->addr);
        else
-- 
2.20.1