errore di segmentazione in getaddrinfo ()

Question

sto ottenendo errore di segmentazione in getaddrinfo ().

Questa è l'analisi dello stack.

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xb7ff4b70 (LWP 26872)]
__res_vinit (statp=0xb7ff4df4, preinit=0) at res_init.c:176
176 res_init.c: No such file or directory.
    in res_init.c
(gdb) bt
#0  __res_vinit (statp=0xb7ff4df4, preinit=0) at res_init.c:176
#1  0x0042fe95 in *__GI___res_ninit (statp=0xb7ff4df4) at res_init.c:142
#2  0x00430ea0 in *__GI___res_maybe_init (resp=0xb7ff4df4, preinit=0) at res_libc.c:122
#3  0x003f86f4 in gaih_inet (name=<value optimized out>, service=<value optimized out>, req=0xb7ff3df8, pai=0xb7ff3db4, naddrs=0xb7ff3da4)
    at ../sysdeps/posix/getaddrinfo.c:690
#4  0x003faa65 in *__GI_getaddrinfo (name=0x8203a68 "api.shoutcast.com", service=0x810ae72 "http", hints=0xb7ff3df8, pai=0xb7ff3e24)
    at ../sysdeps/posix/getaddrinfo.c:2160
#5  0x08050a87 in test_addrinfo () at /kkkk/myaddrinfo.c:33

La fonte della funzione test_addrinfo ();

    #ifndef   NI_MAXHOST
    #define   NI_MAXHOST 1025
    #endif

    struct  addrinfo hints =
    {
        .ai_flags       = 0,        /* Input flags.                 nothing special */
        .ai_family      = PF_UNSPEC,/* Protocol family for socket.  any  */
        .ai_socktype    = SOCK_STREAM,        /* Socket type.                 take any (SOCK_RAW, SOCK_STREAM,  SOCK_DGRAM) */
        .ai_protocol    = IPPROTO_TCP,        /* Protocol for socket.         take any (IPPROTO_TCP and IPPROTO_UDP) */
        .ai_addrlen     = 0,        /* Length of socket address.    always 0 */
        .ai_addr        = NULL,     /* Socket address for socket.   always NULL */
        .ai_canonname   = NULL,     /* Canonical name for service.  always NULL */
        .ai_next        = NULL,     /* Pointer to next in list.     always NULL */
    };



    int test_addrinfo(void)
    {
        struct addrinfo *result = NULL;
        struct addrinfo *res;
        int error;

        /* resolve the domain name into a list of addresses */
        error = getaddrinfo("api.shoutcast.com", "http", &hints, &result);
        if (error != 0)
        {
            fprintf(stderr, "error in getaddrinfo: %s\n", gai_strerror(error));
            return EXIT_FAILURE;
        }

        /* loop over all returned results and do inverse lookup */
        for (res = result; res != NULL; res = res->ai_next)
        {
            char hostname[NI_MAXHOST] = "";

            error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0); 
            if (error != 0)
            {
                fprintf(stderr, "error in getnameinfo: %s\n", gai_strerror(error));
                continue;
            }
            if (*hostname != '\0')
                printf("hostname: %s\n", hostname);
        }

        freeaddrinfo(result);
        return EXIT_SUCCESS;
    }

Dopo l'esecuzione in valgrind, ho ottenuto il seguente registro

    ==00:00:00:07.590 7788==
    ==00:00:00:07.590 7788== Process terminating with default action of signal 11 (SIGSEGV)
    ==00:00:00:07.590 7788==  Bad permissions for mapped region at address 0x4033BDC
    ==00:00:00:07.590 7788==    at 0x4348C8A: __res_vinit (res_init.c:176)
    ==00:00:00:07.645 7788==

Questa test_addrinfo function () viene chiamato da uno strato superiore nella mia applicazione. Ho testato la stessa funzione in un'altra applicazione che ha una sola principale (). Ha funzionato in tale applicazione.

Sto ritenendo sospetto che non sto usando la libreria gnulib corretto o flag di compilazione sbagliate. Eventuali indizi o suggerimenti?

Answer 1

I found the problem. There was stack overflow as the function getaddrinfo() uses alloca() - which allocates memory dynamically but on the stack(and not on heap). This is a very dangerous function.

I tried putting the -fstack-protector-all gcc flag but it was in vain.