USB: keyspan: add a sanity test on "len"

"len" comes from the USB transfer and it's probably correct.  The thing
is that we already have similar checks like:

        if (data[i] >= serial->num_ports) {

So adding a sanity test here matches the rest of the code and is a good
idea.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/usb/serial/keyspan.c b/drivers/usb/serial/keyspan.c
index 3d92394aba3a..025310bc358a 100644
--- a/drivers/usb/serial/keyspan.c
+++ b/drivers/usb/serial/keyspan.c
@@ -741,14 +741,15 @@ static void usa49wg_indat_callback(struct urb *urb)
                 if ((data[i] & 0x80) == 0) {
                         /* no error on any byte */
                         i++;
-                        for (x = 1; x < len ; ++x)
+                        for (x = 1; x < len && i < urb->actual_length; ++x)
                                 tty_insert_flip_char(&port->port,
                                                 data[i++], 0);
                 } else {
                         /*
                          * some bytes had errors, every byte has status
                          */
-                        for (x = 0; x + 1 < len; x += 2) {
+                        for (x = 0; x + 1 < len &&
+                                    i + 1 < urb->actual_length; x += 2) {
                                 int stat = data[i], flag = 0;
 
                                 if (stat & RXERROR_OVERRUN)