shell: free the key in cmd_exec()

source/shell/cmd.c

@@ -72,9 +72,11 @@ void cmd_exec(struct cmd *cmds, const char *line)
 	for (cmd = cmds; cmd->key; ++cmd) {
 		if (strcmp(cmd->key, key) == 0) {
 			cmd->exec(args);
-			return;
+			break;
 		}
 	}
+
+	free(key);
 }
 
 void cmd_loop(const char *show)