scsi: iscsi_tcp: Fix UAF during login when accessing the shost ipaddress

mainline inclusion
from mainline-v6.2-rc6
commit f484a794
category: bugfix
bugzilla: 188443, https://gitee.com/openeuler/kernel/issues/I6I8YD
CVE: NA

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

If during iscsi_sw_tcp_session_create() iscsi_tcp_r2tpool_alloc() fails,
userspace could be accessing the host's ipaddress attr. If we then free the
session via iscsi_session_teardown() while userspace is still accessing the
session we will hit a use after free bug.

Set the tcp_sw_host->session after we have completed session creation and
can no longer fail.

Link: https://lore.kernel.org/r/20230117193937.21244-3-michael.christie@oracle.comSigned-off-by: NMike Christie <michael.christie@oracle.com>
Reviewed-by: NLee Duncan <lduncan@suse.com>
Acked-by: NDing Hui <dinghui@sangfor.com.cn>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NZhong Jinghua <zhongjinghua@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

drivers/scsi/iscsi_tcp.c

@@ -783,7 +783,7 @@ static int iscsi_sw_tcp_host_get_param(struct Scsi_Host *shost,
 				       enum iscsi_host_param param, char *buf)
 {
 	struct iscsi_sw_tcp_host *tcp_sw_host = iscsi_host_priv(shost);
-	struct iscsi_session *session = tcp_sw_host->session;
+	struct iscsi_session *session;
 	struct iscsi_conn *conn;
 	struct iscsi_tcp_conn *tcp_conn;
 	struct iscsi_sw_tcp_conn *tcp_sw_conn;
@@ -792,6 +792,7 @@ static int iscsi_sw_tcp_host_get_param(struct Scsi_Host *shost,
 
 	switch (param) {
 	case ISCSI_HOST_PARAM_IPADDRESS:
+		session = tcp_sw_host->session;
 		if (!session)
 			return -ENOTCONN;
 
@@ -886,11 +887,13 @@ iscsi_sw_tcp_session_create(struct iscsi_endpoint *ep, uint16_t cmds_max,
 	if (!cls_session)
 		goto remove_host;
 	session = cls_session->dd_data;
-	tcp_sw_host = iscsi_host_priv(shost);
-	tcp_sw_host->session = session;
 
 	if (iscsi_tcp_r2tpool_alloc(session))
 		goto remove_session;
+
+	/* We are now fully setup so expose the session to sysfs. */
+	tcp_sw_host = iscsi_host_priv(shost);
+	tcp_sw_host->session = session;
 	return cls_session;
 
 remove_session: