Re: [PATCH v2 2/7] USB: serial: ftdi_sio: Add missing baud rate validation

["Marek Behún" <kabel@kernel.org>]

On Tue, 12 Jul 2022 18:27:28 +0100
Rob Pearce <rob@flitspace.org.uk> wrote:

> On 12/07/2022 12:53, Marek Behún wrote:
> > From: Pali Rohár <pali@kernel.org>
> >
> > Add lower checks for requested baud rate for FT8U232AM, FT232BM, FT2232C,
> > FT232RL, FTX, FT2232H, FT4232H and FT232H. For all of these the minimum
> > baud rate they can generate is 183 Baud.
> >
> > Signed-off-by: Pali Rohár <pali@kernel.org>
> > Tested-by: Marek Behún <kabel@kernel.org>
> > Signed-off-by: Marek Behún <kabel@kernel.org>
> > ---
> >   drivers/usb/serial/ftdi_sio.c | 6 +++---
> >   1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
> > index ea40f367e70c..717b97f4e094 100644
> > --- a/drivers/usb/serial/ftdi_sio.c
> > +++ b/drivers/usb/serial/ftdi_sio.c
> > @@ -1330,7 +1330,7 @@ static u32 get_ftdi_divisor(struct tty_struct *tty,
> >   		}
> >   		break;
> >   	case FT8U232AM: /* 8U232AM chip */
> > -		if (baud <= 3000000) {
> > +		if (baud >= 183 && baud <= 3000000) {
> >   			div_value = ftdi_232am_baud_to_divisor(baud);
> >   		} else {
> >   			dev_dbg(dev, "%s - Baud rate too high!\n", __func__);  
> Due to the above change, this debug message is now incorrect.

Thx for noticing that. I will update. Also I will probably do some more
refactors, I am not yet sure.

Marek

> > @@ -1343,7 +1343,7 @@ static u32 get_ftdi_divisor(struct tty_struct *tty,
> >   	case FT2232C: /* FT2232C chip */
> >   	case FT232RL: /* FT232RL chip */
> >   	case FTX:     /* FT-X series */
> > -		if (baud <= 3000000) {
> > +		if (baud >= 183 && baud <= 3000000) {
> >   			u16 product_id = le16_to_cpu(
> >   				port->serial->dev->descriptor.idProduct);
> >   			if (((product_id == FTDI_NDI_HUC_PID)		||
> > @@ -1367,7 +1367,7 @@ static u32 get_ftdi_divisor(struct tty_struct *tty,
> >   	case FT232H:  /* FT232H chip */
> >   		if ((baud <= 12000000) && (baud >= 1200)) {
> >   			div_value = ftdi_2232h_baud_to_divisor(baud);
> > -		} else if (baud < 1200) {
> > +		} else if (baud >= 183 && baud < 1200) {
> >   			div_value = ftdi_232bm_baud_to_divisor(baud);
> >   		} else {
> >   			dev_dbg(dev, "%s - Baud rate too high!\n", __func__);  
> As above
> 
>