UBI: improve mkvol request validation

Check that volume name is not shorter than 'name_len'.

No need to copy the trailing zero byte because whole array
was zeroed earlier.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/cdev.c

@@ -574,6 +574,10 @@ static int verify_mkvol_req(const struct ubi_device *ubi,
 		goto bad;
 	}
 
+	n = strnlen(req->name, req->name_len + 1);
+	if (n != req->name_len)
+		goto bad;
+
 	return 0;
 
 bad:
@@ -629,12 +633,11 @@ static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
 			break;
 		}
 
+		req.name[req.name_len] = '\0';
 		err = verify_mkvol_req(ubi, &req);
 		if (err)
 			break;
 
-		req.name[req.name_len] = '\0';
-
 		mutex_lock(&ubi->volumes_mutex);
 		err = ubi_create_volume(ubi, &req);
 		mutex_unlock(&ubi->volumes_mutex);

drivers/mtd/ubi/vmt.c

@@ -275,7 +275,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
 	vol->data_pad  = ubi->leb_size % vol->alignment;
 	vol->vol_type  = req->vol_type;
 	vol->name_len  = req->name_len;
-	memcpy(vol->name, req->name, vol->name_len + 1);
+	memcpy(vol->name, req->name, vol->name_len);
 	vol->ubi = ubi;
 
 	/*
@@ -350,7 +350,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
 		vtbl_rec.vol_type = UBI_VID_DYNAMIC;
 	else
 		vtbl_rec.vol_type = UBI_VID_STATIC;
-	memcpy(vtbl_rec.name, vol->name, vol->name_len + 1);
+	memcpy(vtbl_rec.name, vol->name, vol->name_len);
 
 	err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
 	if (err)