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From: Frans Klaver <frans.klaver@xsens.com>
To: <linux-serial@vger.kernel.org>
Cc: Frans Klaver <frans.klaver@xsens.com>,
	Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Ian Campbell <ijc+devicetree@hellion.org.uk>,
	Kumar Gala <galak@codeaurora.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.cz>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: [PATCH 1/3] tty: omap-serial: prevent division by zero
Date: Tue, 29 Jul 2014 17:02:30 +0200	[thread overview]
Message-ID: <1406646152-24698-2-git-send-email-frans.klaver@xsens.com> (raw)
In-Reply-To: <1406646152-24698-1-git-send-email-frans.klaver@xsens.com>

If the chosen baud rate is large enough (e.g. 3.5 megabaud), the
calculated n13 and n16 values in serial_omap_baud_is_mode16 may become
0. This causes a division by zero when calculating the difference
between calculated and desired baud rates. To prevent this, cap n13 and
n16 on 1.

Signed-off-by: Frans Klaver <frans.klaver@xsens.com>
---
 drivers/tty/serial/omap-serial.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index d017cec..e454b7c 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -254,8 +254,16 @@ serial_omap_baud_is_mode16(struct uart_port *port, unsigned int baud)
 {
 	unsigned int n13 = port->uartclk / (13 * baud);
 	unsigned int n16 = port->uartclk / (16 * baud);
-	int baudAbsDiff13 = baud - (port->uartclk / (13 * n13));
-	int baudAbsDiff16 = baud - (port->uartclk / (16 * n16));
+	int baudAbsDiff13;
+	int baudAbsDiff16;
+
+	if (n13 == 0)
+		n13 = 1;
+	if (n16 == 0)
+		n16 = 1;
+
+	baudAbsDiff13 = baud - (port->uartclk / (13 * n13));
+	baudAbsDiff16 = baud - (port->uartclk / (16 * n16));
 	if (baudAbsDiff13 < 0)
 		baudAbsDiff13 = -baudAbsDiff13;
 	if (baudAbsDiff16 < 0)
-- 
1.9.3


WARNING: multiple messages have this Message-ID (diff)
From: Frans Klaver <frans.klaver-MHHw4NDrbWwAvxtiuMwx3w@public.gmane.org>
To: linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: Frans Klaver
	<frans.klaver-MHHw4NDrbWwAvxtiuMwx3w@public.gmane.org>,
	Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>,
	Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
	Ian Campbell
	<ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>,
	Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>,
	Greg Kroah-Hartman
	<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
	Jiri Slaby <jslaby-AlSwsSmVLrQ@public.gmane.org>,
	devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: [PATCH 1/3] tty: omap-serial: prevent division by zero
Date: Tue, 29 Jul 2014 17:02:30 +0200	[thread overview]
Message-ID: <1406646152-24698-2-git-send-email-frans.klaver@xsens.com> (raw)
In-Reply-To: <1406646152-24698-1-git-send-email-frans.klaver-MHHw4NDrbWwAvxtiuMwx3w@public.gmane.org>

If the chosen baud rate is large enough (e.g. 3.5 megabaud), the
calculated n13 and n16 values in serial_omap_baud_is_mode16 may become
0. This causes a division by zero when calculating the difference
between calculated and desired baud rates. To prevent this, cap n13 and
n16 on 1.

Signed-off-by: Frans Klaver <frans.klaver-MHHw4NDrbWwAvxtiuMwx3w@public.gmane.org>
---
 drivers/tty/serial/omap-serial.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index d017cec..e454b7c 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -254,8 +254,16 @@ serial_omap_baud_is_mode16(struct uart_port *port, unsigned int baud)
 {
 	unsigned int n13 = port->uartclk / (13 * baud);
 	unsigned int n16 = port->uartclk / (16 * baud);
-	int baudAbsDiff13 = baud - (port->uartclk / (13 * n13));
-	int baudAbsDiff16 = baud - (port->uartclk / (16 * n16));
+	int baudAbsDiff13;
+	int baudAbsDiff16;
+
+	if (n13 == 0)
+		n13 = 1;
+	if (n16 == 0)
+		n16 = 1;
+
+	baudAbsDiff13 = baud - (port->uartclk / (13 * n13));
+	baudAbsDiff16 = baud - (port->uartclk / (16 * n16));
 	if (baudAbsDiff13 < 0)
 		baudAbsDiff13 = -baudAbsDiff13;
 	if (baudAbsDiff16 < 0)
-- 
1.9.3

--
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  reply	other threads:[~2014-07-29 15:02 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-29 14:52 [RFC PATCH 0/3] omap-serial high-speed fixes/improvements Frans Klaver
2014-07-29 14:52 ` Frans Klaver
2014-07-29 14:52 ` [PATCH 1/3] tty: omap-serial: prevent division by zero Frans Klaver
2014-07-29 15:00   ` Frans Klaver
2014-07-29 15:00     ` Frans Klaver
2014-07-29 14:52 ` [PATCH 2/3] tty: omap-serial: use threaded interrupt handler Frans Klaver
2014-07-29 14:52 ` [PATCH 3/3] tty: omap-serial: support setting of hardware flow control in dts Frans Klaver
2014-07-29 15:02 ` [RFC PATCH 0/3] omap-serial high-speed fixes/improvements Frans Klaver
2014-07-29 15:02   ` Frans Klaver
2014-07-29 15:02   ` Frans Klaver [this message]
2014-07-29 15:02     ` [PATCH 1/3] tty: omap-serial: prevent division by zero Frans Klaver
2014-07-29 15:02   ` [PATCH 2/3] tty: omap-serial: use threaded interrupt handler Frans Klaver
2014-07-29 15:02     ` Frans Klaver
2014-07-29 15:02   ` [PATCH 3/3] tty: omap-serial: support setting of hardware flow control in dts Frans Klaver
2014-07-29 15:02     ` Frans Klaver
2014-08-11 10:09   ` [RFC PATCH 0/3] omap-serial high-speed fixes/improvements Frans Klaver
2014-08-11 10:09     ` Frans Klaver
2014-08-18 13:45 ` Felipe Balbi
2014-08-18 13:45   ` Felipe Balbi
2014-08-18 14:45   ` Frans Klaver
2014-08-18 14:45     ` Frans Klaver
2014-08-19 12:14 ` [RFC PATCHv2 0/4] " Frans Klaver
2014-08-19 12:14   ` Frans Klaver
2014-08-19 12:14   ` Frans Klaver
2014-08-19 12:14   ` [PATCH 1/4] tty: omap-serial: pull out calculation from baud_is_mode16 Frans Klaver
2014-08-19 12:14     ` Frans Klaver
2014-08-19 12:14     ` Frans Klaver
2014-08-19 12:14   ` [PATCH 2/4] tty: omap-serial: prevent division by zero Frans Klaver
2014-08-19 12:14     ` Frans Klaver
2014-08-19 12:14     ` Frans Klaver
2014-08-19 12:14   ` [RFC PATCH 3/4] tty: omap-serial: use threaded interrupt handler Frans Klaver
2014-08-19 12:14     ` Frans Klaver
2014-08-19 12:14     ` Frans Klaver
2014-08-19 18:57     ` Felipe Balbi
2014-08-19 18:57       ` Felipe Balbi
2014-08-19 18:57       ` Felipe Balbi
2014-08-20  6:40       ` Frans Klaver
2014-08-20  6:40         ` Frans Klaver
2014-08-20  6:40         ` Frans Klaver
2014-08-20 16:06         ` Felipe Balbi
2014-08-20 16:06           ` Felipe Balbi
2014-08-20 16:06           ` Felipe Balbi
2014-08-21 21:41           ` Frans Klaver
2014-08-21 21:41             ` Frans Klaver
2014-08-21 21:41             ` Frans Klaver
2014-08-21 21:48             ` Felipe Balbi
2014-08-21 21:48               ` Felipe Balbi
2014-08-21 21:48               ` Felipe Balbi
2014-08-21 22:07               ` Frans Klaver
2014-08-21 22:07                 ` Frans Klaver
2014-08-22 14:02       ` Frans Klaver
2014-08-22 14:02         ` Frans Klaver
2014-08-22 14:02         ` Frans Klaver
2014-08-19 12:14   ` [PATCH 4/4] tty: omap-serial: support setting of hardware flow control in dts Frans Klaver
2014-08-19 12:14     ` Frans Klaver
2014-08-19 12:14     ` Frans Klaver

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