ksmbd: fix NULL pointer dereference in smb2_get_info_filesystem()

mainline inclusion
from mainline-v6.4-rc1
commit 3ac00a2a
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I74FF8
CVE: CVE-2023-32248

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3ac00a2ab69b34189942afa9e862d5170cdcb018



--------------------------------

If share is , share->path is NULL and it cause NULL pointer
dereference issue.

Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-20479
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: ZhaoLong Wang <wangzhaolong1@huawei.com>