fix: net_lwip2_dns_recv_cb有可能内存泄漏,改严谨一些

components/network/adapter_lwip2/net_lwip2.c

@@ -503,6 +503,8 @@ static err_t net_lwip2_dns_recv_cb(void *arg, struct udp_pcb *pcb, struct pbuf *
 					pbuf_take(p, tx_msg_buf.Data, tx_msg_buf.Pos);
 					prvlwip.dns_udp[adapter_index]->local_ip = prvlwip.lwip_netif[adapter_index]->ip_addr;
 					udp_sendto_if(prvlwip.dns_udp[adapter_index], out_p, &prvlwip.dns_client.dns_server[i], DNS_SERVER_PORT, prvlwip.lwip_netif[adapter_index]);
+				}
+				if (out_p) {
 					pbuf_free(out_p);
 				}
 				OS_DeInitBuffer(&tx_msg_buf);