From: Johan Hovold <johan@kernel.org>
Date: Thu, 11 May 2017 09:41:21 +0000 (+0200)
Subject: USB: serial: io_ti: fix div-by-zero in set_termios
X-Git-Tag: v3.2.93~99
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5b044cee0ef9b5f61bca80be15a019eb4ffa6a09;p=thirdparty%2Fkernel%2Fstable.git

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: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/drivers/usb/serial/io_ti.c b/drivers/usb/serial/io_ti.c
index a4177561d09a2..86c8efd49583d 100644
--- a/drivers/usb/serial/io_ti.c
+++ b/drivers/usb/serial/io_ti.c
@@ -2412,8 +2412,11 @@ 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);