[PATCH] serial: Fix crash if the minimum rate of the device is > 9600 baud

[PATCH] serial: Fix crash if the minimum rate of the device is > 9600 baud

[Alan Cox]

(Resend for -next)

In that situation if the old rate is invalid and the new rate is invalid
and the chip cannot do 9600 baud we report zero, which makes all the
drivers explode.

Instead force the rate based on min/max

Signed-off-by: Alan Cox <alan@linux.intel.com>
---

 drivers/serial/serial_core.c |   17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)


diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index fa4f170..07fe320 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -385,13 +385,20 @@ uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
 		}
 
 		/*
-		 * As a last resort, if the quotient is zero,
-		 * default to 9600 bps
+		 * As a last resort, if the range cannot be met then clip to
+		 * the nearest chip supported rate.
 		 */
-		if (!hung_up)
-			tty_termios_encode_baud_rate(termios, 9600, 9600);
+		if (!hung_up) {
+			if (baud <= min)                
+				tty_termios_encode_baud_rate(termios,
+							min + 1, min + 1);
+			else
+				tty_termios_encode_baud_rate(termios,
+							max - 1, max - 1);
+		}
 	}
-
+	/* Should never happen */
+	WARN_ON(1);
 	return 0;
 }
 

Re: [PATCH] serial: Fix crash if the minimum rate of the device is > 9600 baud

[Greg KH]

On Mon, Jan 04, 2010 at 04:26:21PM +0000, Alan Cox wrote:
> 
> (Resend for -next)
> 
> In that situation if the old rate is invalid and the new rate is invalid
> and the chip cannot do 9600 baud we report zero, which makes all the
> drivers explode.
> 
> Instead force the rate based on min/max

Is this something that should go into 2.6.33 and backport to older
kernels?

thanks,

greg k-h