[PATCH v5 6/9] scsi: target: iscsit: free cmds before session free

[Mike Christie <michael.christie@oracle.com>]

From: Dmitry Bogdanov <d.bogdanov@yadro.com>

Commands from recovery entries are freed after its session has been
closed. That leads to use-after-free at command free or NPE with such
call trace:

Time2Retain timer expired for SID: 1, cleaning up iSCSI session.
BUG: kernel NULL pointer dereference, address: 0000000000000140
RIP: 0010:sbitmap_queue_clear+0x3a/0xa0
Call Trace:
 target_release_cmd_kref+0xd1/0x1f0 [target_core_mod]
 transport_generic_free_cmd+0xd1/0x180 [target_core_mod]
 iscsit_free_cmd+0x53/0xd0 [iscsi_target_mod]
 iscsit_free_connection_recovery_entries+0x29d/0x320 [iscsi_target_mod]
 iscsit_close_session+0x13a/0x140 [iscsi_target_mod]
 iscsit_check_post_dataout+0x440/0x440 [iscsi_target_mod]
 call_timer_fn+0x24/0x140

Move cleanup of recovery enrties to before session freeing.

Reported-by: Forza <forza@tnonline.net>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Maurizio Lombardi <mlombard@redhat.com>
---
 drivers/target/iscsi/iscsi_target.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 83b007141229..26634dbea9b8 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -4529,6 +4529,9 @@ int iscsit_close_session(struct iscsit_session *sess, bool can_sleep)
 	iscsit_stop_time2retain_timer(sess);
 	spin_unlock_bh(&se_tpg->session_lock);
 
+	if (sess->sess_ops->ErrorRecoveryLevel == 2)
+		iscsit_free_connection_recovery_entries(sess);
+
 	/*
 	 * transport_deregister_session_configfs() will clear the
 	 * struct se_node_acl->nacl_sess pointer now as a iscsi_np process context
@@ -4552,9 +4555,6 @@ int iscsit_close_session(struct iscsit_session *sess, bool can_sleep)
 
 	transport_deregister_session(sess->se_sess);
 
-	if (sess->sess_ops->ErrorRecoveryLevel == 2)
-		iscsit_free_connection_recovery_entries(sess);
-
 	iscsit_free_all_ooo_cmdsns(sess);
 
 	spin_lock_bh(&se_tpg->session_lock);
-- 
2.25.1