UDP server on LwIP socket falls into hard fault if input string longer than 19 bytes

Question

I think it because of NULL pointer exception. My embedded system consists of STM32F4, FreeRTOS and LwIP. Core was taken from ST example. Here is the code of thread of simple UDP server.

#include <string.h>
#include <stdbool.h>
#include <stdlib.h>
#include "lwip/sockets.h"
#include "./udpCLI.h"
//#include "Sledge.h" //for assert_amsg(), which print what and where fails before stop execution

static void udpCLI_thread(void *arg) 
{
    int sockfd; // socket file descriptor
    const uint16_t serverport = UDP_PORT_NUMBER_CLI;
    struct sockaddr_in serveraddr = {0}, clientaddr = {0};
    socklen_t addrlen;// = sizeof(struct sockaddr_in);
    const uint16_t bufin_SIZE = 200, bufout_SIZE = 1024;
    char *bufin  = malloc(bufin_SIZE);  assert_amsg(bufin != NULL);  // stops execution with printing message "ASSERT FAILED "bufin != NULL" in file udp_cli.c:42" in stdout/stderr
    char *bufout = malloc(bufout_SIZE); assert_amsg(bufout != NULL);

    LWIP_UNUSED_ARG(arg);  //(void)arg;

    debugf2( "udpCLI_thread"NEWLINE );  

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    assert_msg("udpCLI_thread: ERROR opening socket", sockfd>=0);

    /*
     * build the server's Internet address
     */
    serveraddr.sin_family = AF_INET;
    serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
    serveraddr.sin_port = htons(serverport);

    /* 
     * bind: associate the socket with a port 
     */
    if( bind(sockfd, (struct sockaddr *) &serveraddr, sizeof(serveraddr)) < 0 ) 
        error("udpCLI_thread: ERROR on binding");

    // main loop: wait for a datagram, then echo it
    while(1)
    {
        addrlen = sizeof(struct sockaddr_in);  // THIS DID NOT HELP
        // recvfrom: receive a UDP datagram from a client
        int n = recvfrom(sockfd, bufin, bufin_SIZE, /*flags*/0, (struct sockaddr*)&clientaddr, &addrlen);
        // handle rusult
        //if (n < 0)
        // future process and response
        //....
}

Program control never returns from recvfrom() function if input message length is more than 19 bytes. And never returns from function sys_arch_mbox_fetch(&conn->recvmbox, &buf, 0); in function netconn_recv_data() in file api_lib.c at line 371.
Please help to resolve this problem.

Answer 1

That was my mistake. The problem was with wrong memory allocation and release in another task.
I thank all who sympathized.