iser-target: Fix possible use-after-free in connection establishment error

In case we fail to establish the connection we must drain our pre-posted
login recieve work request before continuing safely with connection
teardown.

Fixes: a060b56 ("IB/core: generic RDMA READ/WRITE API")
Cc: <[email protected]> # 4.7+
Reported-by: Amrani, Ram <[email protected]>
Signed-off-by: Sagi Grimberg <[email protected]>
Signed-off-by: Doug Ledford <[email protected]>

Author: sagigrimberg

drivers/infiniband/ulp/isert/ib_isert.c

@@ -741,6 +741,7 @@ isert_connect_error(struct rdma_cm_id *cma_id)
 {
 	struct isert_conn *isert_conn = cma_id->qp->qp_context;
 
+	ib_drain_qp(isert_conn->qp);
 	list_del_init(&isert_conn->node);
 	isert_conn->cm_id = NULL;
 	isert_put_conn(isert_conn);