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: v4.14-rc1~869^2^2~2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6aeb75e6adfaed16e58780309613a578fe1ee90b;p=platform%2Fkernel%2Flinux-rpi.git

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

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")
Cc: stable <stable@vger.kernel.org>     # 2.6.12
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---

diff --git a/drivers/usb/serial/io_ti.c b/drivers/usb/serial/io_ti.c
index 87798e6..6cefb9c 100644
--- a/drivers/usb/serial/io_ti.c
+++ b/drivers/usb/serial/io_ti.c
@@ -2336,8 +2336,11 @@ 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);