From: Wang Qing <wangqing@vivo.com>
Date: Mon, 1 Mar 2021 20:01:33 +0800
Subject: s390/cio: return -EFAULT if copy_to_user() fails
Git-commit: 51c44babdc19aaf882e1213325a0ba291573308f
Patch-mainline: v5.12-rc3
References: git-fixes

The copy_to_user() function returns the number of bytes remaining to be
copied, but we want to return -EFAULT if the copy doesn't complete.

Fixes: e01bcdd61320 ("vfio: ccw: realize VFIO_DEVICE_GET_REGION_INFO ioctl")
Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/1614600093-13992-1-git-send-email-wangqing@vivo.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/cio/vfio_ccw_ops.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -331,7 +331,7 @@ static ssize_t vfio_ccw_mdev_ioctl(struc
 		if (ret)
 			return ret;
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		return copy_to_user((void __user *)arg, &info, minsz) ? -EFAULT : 0;
 	}
 	case VFIO_DEVICE_GET_REGION_INFO:
 	{
@@ -352,7 +352,7 @@ static ssize_t vfio_ccw_mdev_ioctl(struc
 		if (ret)
 			return ret;
 
-		return copy_to_user((void __user *)arg, &info, minsz);
+		return copy_to_user((void __user *)arg, &info, minsz) ? -EFAULT : 0;
 	}
 	case VFIO_DEVICE_GET_IRQ_INFO:
 	{