IB/isert: Fix possible list corruption in CMA handler

When ib_isert module receives connection error event, it is
releasing the isert session and removes corresponding list
node but it doesn't take appropriate mutex lock to remove
the list node.  This can lead to linked  list corruption

Fixes: bd37922 ("iser-target: Fix pending connections handling in target stack shutdown sequnce")
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Saravanan Vajravel <saravanan.vajravel@broadcom.com>
Link: https://lore.kernel.org/r/20230606102531.162967-3-saravanan.vajravel@broadcom.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

Author: Saravanan Vajravel

drivers/infiniband/ulp/isert/ib_isert.c

@@ -657,9 +657,13 @@ static int
 isert_connect_error(struct rdma_cm_id *cma_id)
 {
 	struct isert_conn *isert_conn = cma_id->qp->qp_context;
+	struct isert_np *isert_np = cma_id->context;
 
 	ib_drain_qp(isert_conn->qp);
+
+	mutex_lock(&isert_np->mutex);
 	list_del_init(&isert_conn->node);
+	mutex_unlock(&isert_np->mutex);
 	isert_conn->cm_id = NULL;
 	isert_put_conn(isert_conn);