ice: Check for null pointer dereference when setting rings

Without this check rebuild vsi can lead to kernel panic.
Signed-off-by: NMichal Swiatkowski <michal.swiatkowski@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ice/ice_main.c

@@ -4303,8 +4303,13 @@ int ice_vsi_setup_tx_rings(struct ice_vsi *vsi)
 	}
 
 	ice_for_each_txq(vsi, i) {
-		vsi->tx_rings[i]->netdev = vsi->netdev;
-		err = ice_setup_tx_ring(vsi->tx_rings[i]);
+		struct ice_ring *ring = vsi->tx_rings[i];
+
+		if (!ring)
+			return -EINVAL;
+
+		ring->netdev = vsi->netdev;
+		err = ice_setup_tx_ring(ring);
 		if (err)
 			break;
 	}
@@ -4329,8 +4334,13 @@ int ice_vsi_setup_rx_rings(struct ice_vsi *vsi)
 	}
 
 	ice_for_each_rxq(vsi, i) {
-		vsi->rx_rings[i]->netdev = vsi->netdev;
-		err = ice_setup_rx_ring(vsi->rx_rings[i]);
+		struct ice_ring *ring = vsi->rx_rings[i];
+
+		if (!ring)
+			return -EINVAL;
+
+		ring->netdev = vsi->netdev;
+		err = ice_setup_rx_ring(ring);
 		if (err)
 			break;
 	}