net: liquidio: fix a NULL pointer dereference

In case octeon_alloc_soft_command fails, the fix reports the
error and returns to avoid NULL pointer dereference.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/liquidio/lio_main.c

@@ -1192,6 +1192,11 @@ static void send_rx_ctrl_cmd(struct lio *lio, int start_stop)
 	sc = (struct octeon_soft_command *)
 		octeon_alloc_soft_command(oct, OCTNET_CMD_SIZE,
 					  16, 0);
+	if (!sc) {
+		netif_info(lio, rx_err, lio->netdev,
+			   "Failed to allocate octeon_soft_command\n");
+		return;
+	}
 
 	ncmd = (union octnet_cmd *)sc->virtdptr;