pl2303: pl2303_update_line_status data length fix

Minimum data length must be UART_STATE + 1, as data[UART_STATE] is being accessed for the new line_state. Although PL-2303 hardware is not expected to send data with exactly UART_STATE length, this keeps it on the safe side.

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@@ -826,7 +826,7 @@ static void pl2303_update_line_status(st
 	struct pl2303_private *priv = usb_get_serial_port_data(port);
 	unsigned long flags;
 	u8 status_idx = UART_STATE;
-	u8 length = UART_STATE;
+	u8 length = UART_STATE + 1;
 
 	if ((le16_to_cpu(port->serial->dev->descriptor.idVendor) == SIEMENS_VENDOR_ID) &&
 	    (le16_to_cpu(port->serial->dev->descriptor.idProduct) == SIEMENS_PRODUCT_ID_X65)) {

--
PGP-Key 0xD40E0E7A

IMHO not, no. The PL-2303 interrupt IN endpoint has a 10 bytes FIFO and (as far as I've observed from the type_1 model) always sends packets with exactly this size. The UART_STATE is located at offset 0x08, therefore the minimum packet length we need is 0x09 (UART_STATE + 1).

Here are the two different byte sequences from that endpoint I picked up; the first with a terminal on the serial end, the second without one (both times using the patched pl2303 module with debug=1):

a1 20 00 00 00 00 02 00 00 00
a1 20 00 00 00 00 02 00 82 00

Note the UART_STATE byte with the DSR and CTS bits set in the second case.

In the unlikely case that some weird hardware sends a packet with exactly UART_STATE (8) bytes length, yes, we do. Normal PL-2303 hardware _should_ cause no trouble, as it always sends 10 bytes (at least my hardware does), therefore my side note "this keeps it on the safe side".

Yes, I have.

Kind regards,
Horst

PGP-Key 0xD40E0E7A