nvmet-rdma: fix bonding failover possible NULL deref

RDMA_CM_EVENT_ADDR_CHANGE event occur in the case of bonding failover
on normal as well as on listening cm_ids. Hence this event will
immediately trigger a NULL dereference trying to disconnect a queue
for a cm_id that actually belongs to the port.

To fix this we provide a different handler for the listener cm_ids
that will defer a work to disable+(re)enable the port which essentially
destroys and setups another listener cm_id

Reported-by: Alex Lyakas <alex@zadara.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Tested-by: Alex Lyakas <alex@zadara.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Author: sagigrimberg

drivers/nvme/target/rdma.c

@@ -105,6 +105,13 @@ struct nvmet_rdma_queue {
 	struct list_head	queue_list;
 };
 
+struct nvmet_rdma_port {
+	struct nvmet_port	*nport;
+	struct sockaddr_storage addr;
+	struct rdma_cm_id	*cm_id;
+	struct delayed_work	repair_work;
+};
+
 struct nvmet_rdma_device {
 	struct ib_device	*device;
 	struct ib_pd		*pd;
@@ -917,7 +924,8 @@ static void nvmet_rdma_free_dev(struct kref *ref)
 static struct nvmet_rdma_device *
 nvmet_rdma_find_get_device(struct rdma_cm_id *cm_id)
 {
-	struct nvmet_port *port = cm_id->context;
+	struct nvmet_rdma_port *port = cm_id->context;
+	struct nvmet_port *nport = port->nport;
 	struct nvmet_rdma_device *ndev;
 	int inline_page_count;
 	int inline_sge_count;
@@ -934,17 +942,17 @@ nvmet_rdma_find_get_device(struct rdma_cm_id *cm_id)
 	if (!ndev)
 		goto out_err;
 
-	inline_page_count = num_pages(port->inline_data_size);
+	inline_page_count = num_pages(nport->inline_data_size);
 	inline_sge_count = max(cm_id->device->attrs.max_sge_rd,
 				cm_id->device->attrs.max_recv_sge) - 1;
 	if (inline_page_count > inline_sge_count) {
 		pr_warn("inline_data_size %d cannot be supported by device %s. Reducing to %lu.\n",
-			port->inline_data_size, cm_id->device->name,
+			nport->inline_data_size, cm_id->device->name,
 			inline_sge_count * PAGE_SIZE);
-		port->inline_data_size = inline_sge_count * PAGE_SIZE;
+		nport->inline_data_size = inline_sge_count * PAGE_SIZE;
 		inline_page_count = inline_sge_count;
 	}
-	ndev->inline_data_size = port->inline_data_size;
+	ndev->inline_data_size = nport->inline_data_size;
 	ndev->inline_page_count = inline_page_count;
 	ndev->device = cm_id->device;
 	kref_init(&ndev->ref);
@@ -1272,6 +1280,7 @@ static int nvmet_rdma_cm_accept(struct rdma_cm_id *cm_id,
 static int nvmet_rdma_queue_connect(struct rdma_cm_id *cm_id,
 		struct rdma_cm_event *event)
 {
+	struct nvmet_rdma_port *port = cm_id->context;
 	struct nvmet_rdma_device *ndev;
 	struct nvmet_rdma_queue *queue;
 	int ret = -EINVAL;
@@ -1287,7 +1296,7 @@ static int nvmet_rdma_queue_connect(struct rdma_cm_id *cm_id,
 		ret = -ENOMEM;
 		goto put_device;
 	}
-	queue->port = cm_id->context;
+	queue->port = port->nport;
 
 	if (queue->host_qid == 0) {
 		/* Let inflight controller teardown complete */
@@ -1412,7 +1421,7 @@ static void nvmet_rdma_queue_connect_fail(struct rdma_cm_id *cm_id,
 static int nvmet_rdma_device_removal(struct rdma_cm_id *cm_id,
 		struct nvmet_rdma_queue *queue)
 {
-	struct nvmet_port *port;
+	struct nvmet_rdma_port *port;
 
 	if (queue) {
 		/*
@@ -1431,7 +1440,7 @@ static int nvmet_rdma_device_removal(struct rdma_cm_id *cm_id,
 	 * cm_id destroy. use atomic xchg to make sure
 	 * we don't compete with remove_port.
 	 */
-	if (xchg(&port->priv, NULL) != cm_id)
+	if (xchg(&port->cm_id, NULL) != cm_id)
 		return 0;
 
 	/*
@@ -1462,6 +1471,13 @@ static int nvmet_rdma_cm_handler(struct rdma_cm_id *cm_id,
 		nvmet_rdma_queue_established(queue);
 		break;
 	case RDMA_CM_EVENT_ADDR_CHANGE:
+		if (!queue) {
+			struct nvmet_rdma_port *port = cm_id->context;
+
+			schedule_delayed_work(&port->repair_work, 0);
+			break;
+		}
+		/* FALLTHROUGH */
 	case RDMA_CM_EVENT_DISCONNECTED:
 	case RDMA_CM_EVENT_TIMEWAIT_EXIT:
 		nvmet_rdma_queue_disconnect(queue);
@@ -1504,42 +1520,19 @@ static void nvmet_rdma_delete_ctrl(struct nvmet_ctrl *ctrl)
 	mutex_unlock(&nvmet_rdma_queue_mutex);
 }
 
-static int nvmet_rdma_add_port(struct nvmet_port *port)
+static void nvmet_rdma_disable_port(struct nvmet_rdma_port *port)
 {
-	struct rdma_cm_id *cm_id;
-	struct sockaddr_storage addr = { };
-	__kernel_sa_family_t af;
-	int ret;
-
-	switch (port->disc_addr.adrfam) {
-	case NVMF_ADDR_FAMILY_IP4:
-		af = AF_INET;
-		break;
-	case NVMF_ADDR_FAMILY_IP6:
-		af = AF_INET6;
-		break;
-	default:
-		pr_err("address family %d not supported\n",
-				port->disc_addr.adrfam);
-		return -EINVAL;
-	}
+	struct rdma_cm_id *cm_id = xchg(&port->cm_id, NULL);
 
-	if (port->inline_data_size < 0) {
-		port->inline_data_size = NVMET_RDMA_DEFAULT_INLINE_DATA_SIZE;
-	} else if (port->inline_data_size > NVMET_RDMA_MAX_INLINE_DATA_SIZE) {
-		pr_warn("inline_data_size %u is too large, reducing to %u\n",
-			port->inline_data_size,
-			NVMET_RDMA_MAX_INLINE_DATA_SIZE);
-		port->inline_data_size = NVMET_RDMA_MAX_INLINE_DATA_SIZE;
-	}
+	if (cm_id)
+		rdma_destroy_id(cm_id);
+}
 
-	ret = inet_pton_with_scope(&init_net, af, port->disc_addr.traddr,
-			port->disc_addr.trsvcid, &addr);
-	if (ret) {
-		pr_err("malformed ip/port passed: %s:%s\n",
-			port->disc_addr.traddr, port->disc_addr.trsvcid);
-		return ret;
-	}
+static int nvmet_rdma_enable_port(struct nvmet_rdma_port *port)
+{
+	struct sockaddr *addr = (struct sockaddr *)&port->addr;
+	struct rdma_cm_id *cm_id;
+	int ret;
 
 	cm_id = rdma_create_id(&init_net, nvmet_rdma_cm_handler, port,
 			RDMA_PS_TCP, IB_QPT_RC);
@@ -1558,42 +1551,112 @@ static int nvmet_rdma_add_port(struct nvmet_port *port)
 		goto out_destroy_id;
 	}
 
-	ret = rdma_bind_addr(cm_id, (struct sockaddr *)&addr);
+	ret = rdma_bind_addr(cm_id, addr);
 	if (ret) {
-		pr_err("binding CM ID to %pISpcs failed (%d)\n",
-			(struct sockaddr *)&addr, ret);
+		pr_err("binding CM ID to %pISpcs failed (%d)\n", addr, ret);
 		goto out_destroy_id;
 	}
 
 	ret = rdma_listen(cm_id, 128);
 	if (ret) {
-		pr_err("listening to %pISpcs failed (%d)\n",
-			(struct sockaddr *)&addr, ret);
+		pr_err("listening to %pISpcs failed (%d)\n", addr, ret);
 		goto out_destroy_id;
 	}
 
-	pr_info("enabling port %d (%pISpcs)\n",
-		le16_to_cpu(port->disc_addr.portid), (struct sockaddr *)&addr);
-	port->priv = cm_id;
+	port->cm_id = cm_id;
 	return 0;
 
 out_destroy_id:
 	rdma_destroy_id(cm_id);
 	return ret;
 }
 
-static void nvmet_rdma_remove_port(struct nvmet_port *port)
+static void nvmet_rdma_repair_port_work(struct work_struct *w)
 {
-	struct rdma_cm_id *cm_id = xchg(&port->priv, NULL);
+	struct nvmet_rdma_port *port = container_of(to_delayed_work(w),
+			struct nvmet_rdma_port, repair_work);
+	int ret;
 
-	if (cm_id)
-		rdma_destroy_id(cm_id);
+	nvmet_rdma_disable_port(port);
+	ret = nvmet_rdma_enable_port(port);
+	if (ret)
+		schedule_delayed_work(&port->repair_work, 5 * HZ);
+}
+
+static int nvmet_rdma_add_port(struct nvmet_port *nport)
+{
+	struct nvmet_rdma_port *port;
+	__kernel_sa_family_t af;
+	int ret;
+
+	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	nport->priv = port;
+	port->nport = nport;
+	INIT_DELAYED_WORK(&port->repair_work, nvmet_rdma_repair_port_work);
+
+	switch (nport->disc_addr.adrfam) {
+	case NVMF_ADDR_FAMILY_IP4:
+		af = AF_INET;
+		break;
+	case NVMF_ADDR_FAMILY_IP6:
+		af = AF_INET6;
+		break;
+	default:
+		pr_err("address family %d not supported\n",
+			nport->disc_addr.adrfam);
+		ret = -EINVAL;
+		goto out_free_port;
+	}
+
+	if (nport->inline_data_size < 0) {
+		nport->inline_data_size = NVMET_RDMA_DEFAULT_INLINE_DATA_SIZE;
+	} else if (nport->inline_data_size > NVMET_RDMA_MAX_INLINE_DATA_SIZE) {
+		pr_warn("inline_data_size %u is too large, reducing to %u\n",
+			nport->inline_data_size,
+			NVMET_RDMA_MAX_INLINE_DATA_SIZE);
+		nport->inline_data_size = NVMET_RDMA_MAX_INLINE_DATA_SIZE;
+	}
+
+	ret = inet_pton_with_scope(&init_net, af, nport->disc_addr.traddr,
+			nport->disc_addr.trsvcid, &port->addr);
+	if (ret) {
+		pr_err("malformed ip/port passed: %s:%s\n",
+			nport->disc_addr.traddr, nport->disc_addr.trsvcid);
+		goto out_free_port;
+	}
+
+	ret = nvmet_rdma_enable_port(port);
+	if (ret)
+		goto out_free_port;
+
+	pr_info("enabling port %d (%pISpcs)\n",
+		le16_to_cpu(nport->disc_addr.portid),
+		(struct sockaddr *)&port->addr);
+
+	return 0;
+
+out_free_port:
+	kfree(port);
+	return ret;
+}
+
+static void nvmet_rdma_remove_port(struct nvmet_port *nport)
+{
+	struct nvmet_rdma_port *port = nport->priv;
+
+	cancel_delayed_work_sync(&port->repair_work);
+	nvmet_rdma_disable_port(port);
+	kfree(port);
 }
 
 static void nvmet_rdma_disc_port_addr(struct nvmet_req *req,
-		struct nvmet_port *port, char *traddr)
+		struct nvmet_port *nport, char *traddr)
 {
-	struct rdma_cm_id *cm_id = port->priv;
+	struct nvmet_rdma_port *port = nport->priv;
+	struct rdma_cm_id *cm_id = port->cm_id;
 
 	if (inet_addr_is_any((struct sockaddr *)&cm_id->route.addr.src_addr)) {
 		struct nvmet_rdma_rsp *rsp =
@@ -1603,7 +1666,7 @@ static void nvmet_rdma_disc_port_addr(struct nvmet_req *req,
 
 		sprintf(traddr, "%pISc", addr);
 	} else {
-		memcpy(traddr, port->disc_addr.traddr, NVMF_TRADDR_SIZE);
+		memcpy(traddr, nport->disc_addr.traddr, NVMF_TRADDR_SIZE);
 	}
 }