serial: 8250: fix return error code in serial8250_request_std_resource()

If port->mapbase = NULL in serial8250_request_std_resource() , it need return a error code instead of 0. If uart_set_info() fail to request new regions by serial8250_request_std_resource() but the return value of serial8250_request_std_resource() is 0, The system incorrectly considers that the resource application is successful and does not attempt to restore the old setting. A null pointer reference is triggered when the port resource is later invoked.

Yi Yang committed 4 years ago

Commit 6e690d51 parent 5c5f44e1 file · +3 −1Browse files

Unified · Split

drivers/tty/serial/8250/8250_port.c+3−1

@@ -2975,8 +2975,10 @@ static int serial8250_request_std_resource(struct uart_8250_port *up) · 2974 unmodified lines
2975	2975	case UPIO_MEM32BE:
2976	2976	case UPIO_MEM16:
2977	2977	case UPIO_MEM:
2978		− if (!port->mapbase)
	2978	+ if (!port->mapbase) {
	2979	+ ret = -EINVAL;
2979	2980	break;
	2981	+ }
2980	2982
2981	2983	if (!request_mem_region(port->mapbase, size, "serial")) {
2982	2984	ret = -EBUSY;