chipidea: error on overflow for port_test_write

The write value is 8bit, but currently writing a larger number (eg a doubled
digit) is not errored but instead gets cast and sets off an action probably
undesired.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/usb/chipidea/debug.c b/drivers/usb/chipidea/debug.c
index de5c5092d078..6d23eede4d8c 100644
--- a/drivers/usb/chipidea/debug.c
+++ b/drivers/usb/chipidea/debug.c
@@ -100,6 +100,9 @@ static ssize_t ci_port_test_write(struct file *file, const char __user *ubuf,
         if (sscanf(buf, "%u", &mode) != 1)
                 return -EINVAL;
 
+        if (mode > 255)
+                return -EBADRQC;
+
         pm_runtime_get_sync(ci->dev);
         spin_lock_irqsave(&ci->lock, flags);
         ret = hw_port_test_set(ci, mode);