[PATCH 4.5 143/238] watchdog: rc32434_wdt: fix ioctl error handling

From: Greg Kroah-Hartman
Date: Sun Apr 10 2016 - 16:30:48 EST


4.5-stable review patch. If anyone has any objections, please let me know.

------------------

From: Michael S. Tsirkin <mst@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Wim Van Sebroeck <wim@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/watchdog/rc32434_wdt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/watchdog/rc32434_wdt.c
+++ b/drivers/watchdog/rc32434_wdt.c
@@ -237,7 +237,7 @@ static long rc32434_wdt_ioctl(struct fil
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;
}