watchdog: rc32434_wdt: fix ioctl error handling

commit 10e7ac22cdd4d211cef99afcb9371b70cb175be6 upstream.

Calling return copy_to_user(...) in an ioctl will not do the right thing
if there's a pagefault: copy_to_user returns the number of bytes not
copied in this case.

Fix up watchdog/rc32434_wdt to do
	return copy_to_user(...)) ?  -EFAULT : 0;

instead.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/watchdog/rc32434_wdt.c b/drivers/watchdog/rc32434_wdt.c
index d4c29b5..56dcae7 100644 (file)
--- a/drivers/watchdog/rc32434_wdt.c
+++ b/drivers/watchdog/rc32434_wdt.c
@@ -239,7 +239,7 @@ static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
                        return -EINVAL;
                /* Fall through */
        case WDIOC_GETTIMEOUT:
-               return copy_to_user(argp, &timeout, sizeof(int));
+               return copy_to_user(argp, &timeout, sizeof(int)) ? -EFAULT : 0;
        default:
                return -ENOTTY;
        }