f2fs: check position in move range ioctl

When the move range ioctl is used, check the input and output position and
ensure that it is a non-negative value. Without this check
f2fs_get_dnode_of_data may hit a memmory bug.
Signed-off-by: NDan Robertson <dan@dlrobertson.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -2768,6 +2768,9 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in,
 	if (IS_ENCRYPTED(src) || IS_ENCRYPTED(dst))
 		return -EOPNOTSUPP;
 
+	if (pos_out < 0 || pos_in < 0)
+		return -EINVAL;
+
 	if (src == dst) {
 		if (pos_in == pos_out)
 			return 0;