target/iscsi: Fix iSCSI task reassignment handling

Allocate a task management request structure for all task management
requests, including task reassignment. This change avoids that the
se_tmr->response assignment dereferences an uninitialized se_tmr
pointer.
Reported-by: Moshe David <mdavid@infinidat.com>
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Moshe David <mdavid@infinidat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target.c

@@ -1951,7 +1951,7 @@ iscsit_handle_task_mgt_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	struct iscsi_tm *hdr;
 	int out_of_order_cmdsn = 0, ret;
 	bool sess_ref = false;
-	u8 function;
+	u8 function, tcm_function = TMR_UNKNOWN;
 
 	hdr			= (struct iscsi_tm *) buf;
 	hdr->flags &= ~ISCSI_FLAG_CMD_FINAL;
@@ -1997,10 +1997,6 @@ iscsit_handle_task_mgt_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	 * LIO-Target $FABRIC_MOD
 	 */
 	if (function != ISCSI_TM_FUNC_TASK_REASSIGN) {
-
-		u8 tcm_function;
-		int ret;
-
 		transport_init_se_cmd(&cmd->se_cmd, &iscsi_ops,
 				      conn->sess->se_sess, 0, DMA_NONE,
 				      TCM_SIMPLE_TAG, cmd->sense_buffer + 2);
@@ -2014,15 +2010,14 @@ iscsit_handle_task_mgt_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 			return iscsit_add_reject_cmd(cmd,
 				ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
 		}
-
-		ret = core_tmr_alloc_req(&cmd->se_cmd, cmd->tmr_req,
-					 tcm_function, GFP_KERNEL);
-		if (ret < 0)
-			return iscsit_add_reject_cmd(cmd,
+	}
+	ret = core_tmr_alloc_req(&cmd->se_cmd, cmd->tmr_req, tcm_function,
+				 GFP_KERNEL);
+	if (ret < 0)
+		return iscsit_add_reject_cmd(cmd,
 				ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
 
-		cmd->tmr_req->se_tmr_req = cmd->se_cmd.se_tmr_req;
-	}
+	cmd->tmr_req->se_tmr_req = cmd->se_cmd.se_tmr_req;
 
 	cmd->iscsi_opcode	= ISCSI_OP_SCSI_TMFUNC;
 	cmd->i_state		= ISTATE_SEND_TASKMGTRSP;