USB: serial: io_ti: fix div-by-zero in set_termios

commit 6aeb75e6adfaed16e58780309613a578fe1ee90b upstream.

Fix a division-by-zero in set_termios when debugging is enabled and a
high-enough speed has been requested so that the divisor value becomes
zero.

Instead of just fixing the offending debug statement, cap the baud rate
at the base as a zero divisor value also appears to crash the firmware.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/usb/serial/io_ti.c b/drivers/usb/serial/io_ti.c
index f1a8fdcd8674..e98532feb0cc 100644
--- a/drivers/usb/serial/io_ti.c
+++ b/drivers/usb/serial/io_ti.c
@@ -2349,8 +2349,11 @@ static void change_port_settings(struct tty_struct *tty,
         if (!baud) {
                 /* pick a default, any default... */
                 baud = 9600;
-        } else
+        } else {
+                /* Avoid a zero divisor. */
+                baud = min(baud, 461550);
                 tty_encode_baud_rate(tty, baud, baud);
+        }
 
         edge_port->baud_rate = baud;
         config->wBaudRate = (__u16)((461550L + baud/2) / baud);