[POWERPC] of_serial: Fix possible null dereference.

The of_serial driver queries the current-speed property and attempts
to use it to register the custom_divisor property of the uart_port.
However, if current-speed is not set, then this code will dereference
a bad pointer.  The fix is to only set custom_divisor when a
current-speed property appears in the device tree.

Signed-off-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Signed-off-by: John Linn <john.linn@xilinx.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/serial/of_serial.c b/drivers/serial/of_serial.c
index c0e50a461055..8aacfb78deab 100644
--- a/drivers/serial/of_serial.c
+++ b/drivers/serial/of_serial.c
@@ -56,7 +56,9 @@ static int __devinit of_platform_serial_setup(struct of_device *ofdev,
         port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP
                 | UPF_FIXED_PORT;
         port->dev = &ofdev->dev;
-        port->custom_divisor = *clk / (16 * (*spd));
+        /* If current-speed was set, then try not to change it. */
+        if (spd)
+                port->custom_divisor = *clk / (16 * (*spd));
 
         return 0;
 }