On Mon, 08 Aug 2005, Greg KH wrote: > On Thu, Jul 28, 2005 at 03:32:20PM +0200, Horst Schirmeier wrote: > > 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. > > > > Signed-off-by: Horst Schirmeier <[email protected]> > > --- > > > > --- linux-2.6.13-rc3-git9/drivers/usb/serial/pl2303.c.orig 2005-07-28 14:42:58.000000000 +0200 > > +++ linux-2.6.13-rc3-git9/drivers/usb/serial/pl2303.c 2005-07-28 14:43:16.000000000 +0200 > > @@ -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; > > "safe side" yes, but this will just prevent any line changes from going > back to the user, right? 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. > Hm, how is this working at all, it looks like we overflow the buffer... 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". > Have you tested this change? Yes, I have. > thanks, > > greg k-h Kind regards, Horst -- PGP-Key 0xD40E0E7A
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