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 <ohartoov@nvidia.com>
Reviewed-by: Michael Guralnik <michaelgur@nvidia.com>
Link: https://lore.kernel.org/r/bd924da89d5b4f5291a4a01d9b5ae47c0a9b6a3f.1669636336.git.leonro@nvidia.comSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/core/nldev.c

@@ -1043,6 +1043,10 @@ static int nldev_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
 	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)
@@ -1128,7 +1132,7 @@ static int _nldev_get_dumpit(struct ib_device *device,
 			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;
 	}
@@ -1187,6 +1191,10 @@ static int nldev_port_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
 	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)
@@ -1248,7 +1256,7 @@ static int nldev_port_get_dumpit(struct sk_buff *skb,
 						 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;
 		}
@@ -1290,6 +1298,10 @@ static int nldev_res_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
 	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)
@@ -1321,7 +1333,7 @@ static int _nldev_res_get_dumpit(struct ib_device *device,
 			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;
 	}
@@ -1456,7 +1468,7 @@ static int res_get_common_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
 					 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;
 	}
@@ -1535,7 +1547,7 @@ static int res_get_common_dumpit(struct sk_buff *skb,
 					 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;
 	}
@@ -1797,6 +1809,10 @@ static int nldev_get_chardev(struct sk_buff *skb, struct nlmsghdr *nlh,
 			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);
@@ -1854,6 +1870,10 @@ static int nldev_sys_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
 			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);
@@ -2034,7 +2054,7 @@ static int nldev_stat_set_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
 			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;
@@ -2103,6 +2123,10 @@ static int nldev_stat_del_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
 			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]);
@@ -2173,7 +2197,7 @@ static int stat_get_doit_default_counter(struct sk_buff *skb,
 					 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;
@@ -2261,6 +2285,10 @@ static int stat_get_doit_qp(struct sk_buff *skb, struct nlmsghdr *nlh,
 			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)
@@ -2393,7 +2421,7 @@ static int nldev_stat_get_counter_status_doit(struct sk_buff *skb,
 		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;