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: NNamjae Jeon <linkinjeon@kernel.org>
Signed-off-by: NSteve French <stfrench@microsoft.com>
Signed-off-by: NZhaoLong Wang <wangzhaolong1@huawei.com>

fs/ksmbd/smb2pdu.c

@@ -4867,6 +4867,9 @@ static int smb2_get_info_filesystem(struct ksmbd_work *work,
 	int rc = 0, len;
 	int fs_infoclass_size = 0;
 
+	if (!share->path)
+		return -EIO;
+
 	rc = kern_path(share->path, LOOKUP_NO_SYMLINKS, &path);
 	if (rc) {
 		pr_err("cannot create vfs path\n");