iscsi-target: Fix ISCSI_OP_SCSI_TMFUNC handling for iser

This patch adds target_get_sess_cmd reference counting for
iscsit_handle_task_mgt_cmd(), and adds a target_put_sess_cmd()
for the failure case.

It also fixes a bug where ISCSI_OP_SCSI_TMFUNC type commands
where leaking iscsi_cmd->i_conn_node and eventually triggering
an OOPs during struct isert_conn shutdown.

Cc: stable@vger.kernel.org  # 3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/infiniband/ulp/isert/ib_isert.c

@@ -1200,14 +1200,12 @@ isert_put_cmd(struct isert_cmd *isert_cmd)
 {
 	struct iscsi_cmd *cmd = &isert_cmd->iscsi_cmd;
 	struct isert_conn *isert_conn = isert_cmd->conn;
-	struct iscsi_conn *conn;
+	struct iscsi_conn *conn = isert_conn->conn;
 
 	pr_debug("Entering isert_put_cmd: %p\n", isert_cmd);
 
 	switch (cmd->iscsi_opcode) {
 	case ISCSI_OP_SCSI_CMD:
-		conn = isert_conn->conn;
-
 		spin_lock_bh(&conn->cmd_lock);
 		if (!list_empty(&cmd->i_conn_node))
 			list_del(&cmd->i_conn_node);
@@ -1217,16 +1215,18 @@ isert_put_cmd(struct isert_cmd *isert_cmd)
 			iscsit_stop_dataout_timer(cmd);
 
 		isert_unmap_cmd(isert_cmd, isert_conn);
-		/*
-		 * Fall-through
-		 */
+		transport_generic_free_cmd(&cmd->se_cmd, 0);
+		break;
 	case ISCSI_OP_SCSI_TMFUNC:
+		spin_lock_bh(&conn->cmd_lock);
+		if (!list_empty(&cmd->i_conn_node))
+			list_del(&cmd->i_conn_node);
+		spin_unlock_bh(&conn->cmd_lock);
+
 		transport_generic_free_cmd(&cmd->se_cmd, 0);
 		break;
 	case ISCSI_OP_REJECT:
 	case ISCSI_OP_NOOP_OUT:
-		conn = isert_conn->conn;
-
 		spin_lock_bh(&conn->cmd_lock);
 		if (!list_empty(&cmd->i_conn_node))
 			list_del(&cmd->i_conn_node);

drivers/target/iscsi/iscsi_target.c

@@ -1737,8 +1737,8 @@ iscsit_handle_task_mgt_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	struct se_tmr_req *se_tmr;
 	struct iscsi_tmr_req *tmr_req;
 	struct iscsi_tm *hdr;
-	int out_of_order_cmdsn = 0;
-	int ret;
+	int out_of_order_cmdsn = 0, ret;
+	bool sess_ref = false;
 	u8 function;
 
 	hdr			= (struct iscsi_tm *) buf;
@@ -1794,6 +1794,9 @@ iscsit_handle_task_mgt_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 				      conn->sess->se_sess, 0, DMA_NONE,
 				      MSG_SIMPLE_TAG, cmd->sense_buffer + 2);
 
+		target_get_sess_cmd(conn->sess->se_sess, &cmd->se_cmd, true);
+		sess_ref = true;
+
 		switch (function) {
 		case ISCSI_TM_FUNC_ABORT_TASK:
 			tcm_function = TMR_ABORT_TASK;
@@ -1931,6 +1934,11 @@ attach:
 	 * For connection recovery, this is also the default action for
 	 * TMR TASK_REASSIGN.
 	 */
+	if (sess_ref) {
+		pr_debug("Handle TMR, using sess_ref=true check\n");
+		target_put_sess_cmd(conn->sess->se_sess, &cmd->se_cmd);
+	}
+
 	iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 	return 0;
 }