RDMA/nldev: Add NULL check to silence false warnings

Using nlmsg_put causes static analysis tools to many
false positives of not checking the return value of nlmsg_put.

In all uses in nldev.c, payload parameter is 0 so NULL will never
be returned. So let's add useless checks to silence the warnings.

Signed-off-by: Or Har-Toov <[e-mail]>
Reviewed-by: Michael Guralnik <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Leon Romanovsky <[e-mail]>

drivers/infiniband/core/nldev.c

···
 	nlh = nlmsg_put(msg, NETLINK_CB(skb).portid, nlh->nlmsg_seq,
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_GET),
 			0, 0);
+	if (!nlh) {
+		err = -EMSGSIZE;
+		goto err_free;
+	}
 
 	err = fill_dev_info(msg, device);
 	if (err)
···
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_GET),
 			0, NLM_F_MULTI);
 
-	if (fill_dev_info(skb, device)) {
+	if (!nlh || fill_dev_info(skb, device)) {
 		nlmsg_cancel(skb, nlh);
 		goto out;
 	}
···
 	nlh = nlmsg_put(msg, NETLINK_CB(skb).portid, nlh->nlmsg_seq,
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_GET),
 			0, 0);
+	if (!nlh) {
+		err = -EMSGSIZE;
+		goto err_free;
+	}
 
 	err = fill_port_info(msg, device, port, sock_net(skb->sk));
 	if (err)
···
 						 RDMA_NLDEV_CMD_PORT_GET),
 				0, NLM_F_MULTI);
 
-		if (fill_port_info(skb, device, p, sock_net(skb->sk))) {
+		if (!nlh || fill_port_info(skb, device, p, sock_net(skb->sk))) {
 			nlmsg_cancel(skb, nlh);
 			goto out;
 		}
···
 	nlh = nlmsg_put(msg, NETLINK_CB(skb).portid, nlh->nlmsg_seq,
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_RES_GET),
 			0, 0);
+	if (!nlh) {
+		ret = -EMSGSIZE;
+		goto err_free;
+	}
 
 	ret = fill_res_info(msg, device);
 	if (ret)
···
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_RES_GET),
 			0, NLM_F_MULTI);
 
-	if (fill_res_info(skb, device)) {
+	if (!nlh || fill_res_info(skb, device)) {
 		nlmsg_cancel(skb, nlh);
 		goto out;
 	}
···
 					 RDMA_NL_GET_OP(nlh->nlmsg_type)),
 			0, 0);
 
-	if (fill_nldev_handle(msg, device)) {
+	if (!nlh || fill_nldev_handle(msg, device)) {
 		ret = -EMSGSIZE;
 		goto err_free;
 	}
···
 					 RDMA_NL_GET_OP(cb->nlh->nlmsg_type)),
 			0, NLM_F_MULTI);
 
-	if (fill_nldev_handle(skb, device)) {
+	if (!nlh || fill_nldev_handle(skb, device)) {
 		ret = -EMSGSIZE;
 		goto err;
 	}
···
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV,
 					 RDMA_NLDEV_CMD_GET_CHARDEV),
 			0, 0);
+	if (!nlh) {
+		err = -EMSGSIZE;
+		goto out_nlmsg;
+	}
 
 	data.nl_msg = msg;
 	err = ib_get_client_nl_info(ibdev, client_name, &data);
···
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV,
 					 RDMA_NLDEV_CMD_SYS_GET),
 			0, 0);
+	if (!nlh) {
+		nlmsg_free(msg);
+		return -EMSGSIZE;
+	}
 
 	err = nla_put_u8(msg, RDMA_NLDEV_SYS_ATTR_NETNS_MODE,
 			 (u8)ib_devices_shared_netns);
···
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV,
 					 RDMA_NLDEV_CMD_STAT_SET),
 			0, 0);
-	if (fill_nldev_handle(msg, device) ||
+	if (!nlh || fill_nldev_handle(msg, device) ||
 	    nla_put_u32(msg, RDMA_NLDEV_ATTR_PORT_INDEX, port)) {
 		ret = -EMSGSIZE;
 		goto err_free_msg;
···
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV,
 					 RDMA_NLDEV_CMD_STAT_SET),
 			0, 0);
+	if (!nlh) {
+		ret = -EMSGSIZE;
+		goto err_fill;
+	}
 
 	cntn = nla_get_u32(tb[RDMA_NLDEV_ATTR_STAT_COUNTER_ID]);
 	qpn = nla_get_u32(tb[RDMA_NLDEV_ATTR_RES_LQPN]);
···
 					 RDMA_NLDEV_CMD_STAT_GET),
 			0, 0);
 
-	if (fill_nldev_handle(msg, device) ||
+	if (!nlh || fill_nldev_handle(msg, device) ||
 	    nla_put_u32(msg, RDMA_NLDEV_ATTR_PORT_INDEX, port)) {
 		ret = -EMSGSIZE;
 		goto err_msg;
···
 			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV,
 					 RDMA_NLDEV_CMD_STAT_GET),
 			0, 0);
+	if (!nlh) {
+		ret = -EMSGSIZE;
+		goto err_msg;
+	}
 
 	ret = rdma_counter_get_mode(device, port, &mode, &mask);
 	if (ret)
···
 		0, 0);
 
 	ret = -EMSGSIZE;
-	if (fill_nldev_handle(msg, device) ||
+	if (!nlh || fill_nldev_handle(msg, device) ||
 	    nla_put_u32(msg, RDMA_NLDEV_ATTR_PORT_INDEX, port))
 		goto err_msg;