Re: [PATCH for-4.5] watchdog/rc32434_wdt: fix ioctl error handling

Guenter Roeck
2016-02-28T15:56:59Z

On 02/28/2016 07:44 AM, Michael S. Tsirkin wrote:
> 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.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Acked-by: Guenter Roeck <linux@roeck-us.net>

> ---
>
> Untested.
>
> drivers/watchdog/rc32434_wdt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/watchdog/rc32434_wdt.c b/drivers/watchdog/rc32434_wdt.c
> index 71e78ef..3a75f3b 100644
> --- a/drivers/watchdog/rc32434_wdt.c
> +++ b/drivers/watchdog/rc32434_wdt.c
> @@ -237,7 +237,7 @@ 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;
> }
>