i40e: fix potential NULL pointer dereferencing of pf->vf i40e_sync_vsi_filters()

Add check for pf->vf not being NULL before dereferencing
pf->vf[vsi->vf_id] in updating VSI filter sync.
Add a similar check before dereferencing !pf->vf[vsi->vf_id].trusted
in the condition for clearing promisc mode bit.

Fixes: c87c938 ("i40e: Add VF VLAN pruning")
Signed-off-by: Andrii Staikov <andrii.staikov@intel.com>
Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: CuriousPanCake

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -2609,7 +2609,7 @@ int i40e_sync_vsi_filters(struct i40e_vsi *vsi)
 			retval = i40e_correct_mac_vlan_filters
 				(vsi, &tmp_add_list, &tmp_del_list,
 				 vlan_filters);
-		else
+		else if (pf->vf)
 			retval = i40e_correct_vf_mac_vlan_filters
 				(vsi, &tmp_add_list, &tmp_del_list,
 				 vlan_filters, pf->vf[vsi->vf_id].trusted);
@@ -2782,7 +2782,8 @@ int i40e_sync_vsi_filters(struct i40e_vsi *vsi)
 	}
 
 	/* if the VF is not trusted do not do promisc */
-	if ((vsi->type == I40E_VSI_SRIOV) && !pf->vf[vsi->vf_id].trusted) {
+	if (vsi->type == I40E_VSI_SRIOV && pf->vf &&
+	    !pf->vf[vsi->vf_id].trusted) {
 		clear_bit(__I40E_VSI_OVERFLOW_PROMISC, vsi->state);
 		goto out;
 	}