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

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index fa4f170f2e863ac13b8c22ef24771bb839c0e3b2..7f28307095121766d685350dad865e72f7d312c2 100644 (file)
--- 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;
 }