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From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 23 May 2022 11:33:26 +0300
Subject: vhost-vdpa: return -EFAULT on copy_to_user() failure
Patch-mainline: v5.19-rc1
Git-commit: f4a8686ec7a34f940d36784872036fbacb1b4623
References: jsc#PED-1549

The copy_to_user() function returns the number of bytes remaining to be
copied.  However, we need to return a negative error code, -EFAULT, to
the user.

Fixes: 87f4c217413a ("vhost-vdpa: introduce uAPI to get the number of virtqueue groups")
Fixes: e96ef636f154 ("vhost-vdpa: introduce uAPI to get the number of address spaces")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Message-Id: <YotG1vXKXXSayr63@kili>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/vhost/vdpa.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -609,11 +609,13 @@ static long vhost_vdpa_unlocked_ioctl(st
 		r = vhost_vdpa_get_vring_num(v, argp);
 		break;
 	case VHOST_VDPA_GET_GROUP_NUM:
-		r = copy_to_user(argp, &v->vdpa->ngroups,
-				 sizeof(v->vdpa->ngroups));
+		if (copy_to_user(argp, &v->vdpa->ngroups,
+				 sizeof(v->vdpa->ngroups)))
+			r = -EFAULT;
 		break;
 	case VHOST_VDPA_GET_AS_NUM:
-		r = copy_to_user(argp, &v->vdpa->nas, sizeof(v->vdpa->nas));
+		if (copy_to_user(argp, &v->vdpa->nas, sizeof(v->vdpa->nas)))
+			r = -EFAULT;
 		break;
 	case VHOST_SET_LOG_BASE:
 	case VHOST_SET_LOG_FD: