i40e: Fix potential invalid access when MAC list is empty

[ Upstream commit a556f06338e1d5a85af0e32ecb46e365547f92b9 ]

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.ni@easystack.cn>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_client.c b/drivers/net/ethernet/intel/i40e/i40e_client.c
index 59263551c3838f3cede67d29f2c50c65b87f173c..0b099e5f48163db2f97763e9f00087401e9b8e12 100644 (file)
--- 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