--- x/drivers/infiniband/core/ucma.c
+++ y/drivers/infiniband/core/ucma.c
@@ -272,8 +272,24 @@ static struct ucma_event *ucma_create_ue
 	case RDMA_CM_EVENT_MULTICAST_ERROR:
 		uevent->mc = (struct ucma_multicast *)
 			     event->param.ud.private_data;
-		uevent->resp.uid = uevent->mc->uid;
-		uevent->resp.id = uevent->mc->id;
+		do {
+			struct ucma_multicast *mc;
+			int err = 1;
+
+			xa_lock(&multicast_table);
+			list_for_each_entry(mc, &ctx->mc_list, list)
+				if (mc == uevent->mc) {
+					uevent->resp.uid = uevent->mc->uid;
+					uevent->resp.id = uevent->mc->id;
+					err = 0;
+					break;
+				}
+			xa_unlock(&multicast_table);
+			if (err) {
+				kfree(uevent);
+				return NULL;
+			}
+		} while (0);
 		break;
 	default:
 		uevent->resp.uid = ctx->uid;