[media] ttusb_dec: avoid the risk of go past buffer

Fixes this smatch warning:
	drivers/media/usb/ttusb-dec/ttusb_dec.c:243 ttusb_dec_handle_irq() error: buffer overflow 'rc_keys' 26 <= 126

As the RC keys should be enabled previously, via:
	set_bit(rc_keys[i], input_dev->keybit);

It wouldn't go past the buffer in practice. Yet, as bad
things may happen when going past buffer, it doesn't hurt adding
a check here.

While here, fix CodingStyle issues on the routine.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 18 insertions, 12 deletions

diff --git a/drivers/media/usb/ttusb-dec/ttusb_dec.c b/drivers/media/usb/ttusb-dec/ttusb_dec.c
index 4e36e24cb3a6..4e7671a3a1e4 100644
--- a/drivers/media/usb/ttusb-dec/ttusb_dec.c
+++ b/drivers/media/usb/ttusb-dec/ttusb_dec.c
@@ -206,7 +206,7 @@ static void ttusb_dec_set_model(struct ttusb_dec *dec,
 
 static void ttusb_dec_handle_irq( struct urb *urb)
 {
-        struct ttusb_dec * dec = urb->context;
+        struct ttusb_dec *dec = urb->context;
         char *buffer = dec->irq_buffer;
         int retval;
 
@@ -227,25 +227,31 @@ static void ttusb_dec_handle_irq( struct urb *urb)
                         goto exit;
         }
 
-        if( (buffer[0] == 0x1) && (buffer[2] == 0x15) )  {
-                /* IR - Event */
-                /* this is an fact a bit too simple implementation;
+        if ((buffer[0] == 0x1) && (buffer[2] == 0x15))  {
+                /*
+                 * IR - Event
+                 *
+                 * this is an fact a bit too simple implementation;
                  * the box also reports a keyrepeat signal
                  * (with buffer[3] == 0x40) in an intervall of ~100ms.
                  * But to handle this correctly we had to imlemenent some
                  * kind of timer which signals a 'key up' event if no
                  * keyrepeat signal is received for lets say 200ms.
                  * this should/could be added later ...
-                 * for now lets report each signal as a key down and up*/
-                dprintk("%s:rc signal:%d\n", __func__, buffer[4]);
-                input_report_key(dec->rc_input_dev, rc_keys[buffer[4] - 1], 1);
-                input_sync(dec->rc_input_dev);
-                input_report_key(dec->rc_input_dev, rc_keys[buffer[4] - 1], 0);
-                input_sync(dec->rc_input_dev);
+                 * for now lets report each signal as a key down and up
+                 */
+                if (buffer[4] - 1 < ARRAY_SIZE(rc_keys)) {
+                        dprintk("%s:rc signal:%d\n", __func__, buffer[4]);
+                        input_report_key(dec->rc_input_dev, rc_keys[buffer[4] - 1], 1);
+                        input_sync(dec->rc_input_dev);
+                        input_report_key(dec->rc_input_dev, rc_keys[buffer[4] - 1], 0);
+                        input_sync(dec->rc_input_dev);
+                }
         }
 
-exit:   retval = usb_submit_urb(urb, GFP_ATOMIC);
-        if(retval)
+exit:
+        retval = usb_submit_urb(urb, GFP_ATOMIC);
+        if (retval)
                 printk("%s - usb_commit_urb failed with result: %d\n",
                         __func__, retval);
 }