Discover is showing UMRs when using getaddrinfo/getnameinfo

Question

Hi,
I started playing with the discover (Studio 12.4, Solaris 11.2, x86) tool to check my apps for memory errors etc.
I noticed that I get UMR warnings/errors when using the getaddrinfo()/getnameinfo() socket functions. Why?
me@solaris11_2_x86:/tmp $ cat getaddrinfo.c
#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>
int
main(void)
    struct addrinfo *result, *res;
    int error;
    error = getaddrinfo("www.oracle.com", NULL, NULL, &result);
    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 (*hostname != '\0')
            printf("hostname: %s\n", hostname);
    freeaddrinfo(result);
    return 0;
me@solaris11_2_x86:/tmp $ cc -g getaddrinfo.c -lsocket
me@solaris11_2_x86:/tmp $ discover -w - a.out
me@solaris11_2_x86:/tmp $ ./a.out
ERROR 1 (UMR): accessing uninitialized data "result" at address 0xfeffe650 (4 bytes) on the stack at:
        main() + 0x141  <getaddrinfo.c:14>
                11:        int error;
                12:
                13:        error = getaddrinfo("www.oracle.com", NULL, NULL, &result);
                14:=>      for (res = result; res != NULL; res = res->ai_next)
                15:        {
                16:            char hostname[NI_MAXHOST];
                17:
        _start() + 0x71
ERROR 2 (UMR): accessing uninitialized data "*(result + 16)" at address 0x8080518 (4 bytes) on the heap at:
        main() + 0x247  <getaddrinfo.c:18>
                15:        {
                16:            char hostname[NI_MAXHOST];
                17:
                18:=>          error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0);
                19:            if (*hostname != '\0')
                20:                printf("hostname: %s\n", hostname);
                21:        }
        _start() + 0x71
    was allocated at (32 bytes):
        get_addr() + 0x22f
        _getaddrinfo() + 0x496
        getaddrinfo() + 0x1e
        main() + 0xee  <getaddrinfo.c:13>
                10:        struct addrinfo *result, *res;
                11:        int error;
                12:
                13:=>      error = getaddrinfo("www.oracle.com", NULL, NULL, &result);
                14:        for (res = result; res != NULL; res = res->ai_next)
                15:        {
                16:            char hostname[NI_MAXHOST];
        _start() + 0x71
ERROR 3 (UMR): accessing uninitialized data "*(result + 24)" at address 0x8080520 (4 bytes) on the heap at:
        main() + 0x289  <getaddrinfo.c:18>
                15:        {
                16:            char hostname[NI_MAXHOST];
                17:
                18:=>          error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0);
                19:            if (*hostname != '\0')
                20:                printf("hostname: %s\n", hostname);
                21:        }
        _start() + 0x71
    was allocated at (32 bytes):
        get_addr() + 0x22f
        _getaddrinfo() + 0x496
        getaddrinfo() + 0x1e
        main() + 0xee  <getaddrinfo.c:13>
                10:        struct addrinfo *result, *res;
                11:        int error;
                12:
                13:=>      error = getaddrinfo("www.oracle.com", NULL, NULL, &result);
                14:        for (res = result; res != NULL; res = res->ai_next)
                15:        {
                16:            char hostname[NI_MAXHOST];
        _start() + 0x71
ERROR 4 (PIR): accessing partially initialized data at address 0x8084cd5 (51 bytes) on the heap at:
        __mappedtov4() + 0x134
        getipnodebyaddr() + 0x179
        getnameinfo() + 0xbd
        main() + 0x2b1  <getaddrinfo.c:18>
                15:        {
                16:            char hostname[NI_MAXHOST];
                17:
                18:=>          error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0);
                19:            if (*hostname != '\0')
                20:                printf("hostname: %s\n", hostname);
                21:        }
        _start() + 0x71
    was allocated at (8500 bytes):
        __IPv6_alloc() + 0x39
        getipnodebyaddr() + 0x95
        getnameinfo() + 0xbd
        main() + 0x2b1  <getaddrinfo.c:18>
                15:        {
                16:            char hostname[NI_MAXHOST];
                17:
                18:=>          error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0);
                19:            if (*hostname != '\0')
                20:                printf("hostname: %s\n", hostname);
                21:        }
        _start() + 0x71
ERROR 5 (PIR): accessing partially initialized data at address 0x8086e51 (51 bytes) on the heap at:
        getnameinfo() + 0xf5
        main() + 0x2b1  <getaddrinfo.c:18>
                15:        {
                16:            char hostname[NI_MAXHOST];
                17:
                18:=>          error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0);
                19:            if (*hostname != '\0')
                20:                printf("hostname: %s\n", hostname);
                21:        }
        _start() + 0x71
    was allocated at (8500 bytes):
        __IPv6_alloc() + 0x39
        __mappedtov4() + 0x53
        getipnodebyaddr() + 0x179
        getnameinfo() + 0xbd
        main() + 0x2b1  <getaddrinfo.c:18>
                15:        {
                16:            char hostname[NI_MAXHOST];
                17:
                18:=>          error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0);
                19:            if (*hostname != '\0')
                20:                printf("hostname: %s\n", hostname);
                21:        }
        _start() + 0x71
hostname: a23-43-22-140.deploy.static.akamaitechnologies.com
ERROR 6 (UMR): accessing uninitialized data "*(result + 28)" at address 0x8080524 (4 bytes) on the heap at:
        main() + 0x37a  <getaddrinfo.c:14>
                11:        int error;
                12:
                13:        error = getaddrinfo("www.oracle.com", NULL, NULL, &result);
                14:=>      for (res = result; res != NULL; res = res->ai_next)
                15:        {
                16:            char hostname[NI_MAXHOST];
                17:
        _start() + 0x71
    was allocated at (32 bytes):
        get_addr() + 0x22f
        _getaddrinfo() + 0x496
        getaddrinfo() + 0x1e
        main() + 0xee  <getaddrinfo.c:13>
                10:        struct addrinfo *result, *res;
                11:        int error;
                12:
                13:=>      error = getaddrinfo("www.oracle.com", NULL, NULL, &result);
                14:        for (res = result; res != NULL; res = res->ai_next)
                15:        {
                16:            char hostname[NI_MAXHOST];
        _start() + 0x71
***************** Discover Memory Report *****************
No allocated memory left on program exit.
DISCOVER SUMMARY:
        unique errors   : 6 (6 total)
        unique warnings : 0 (0 total)

Answer 1

Hi,
Thanks for reporting the issue.
Discover instruments the target binary and dependent libraries in order to correctly identify memory errors. For this particular program, the dependent library libsocket.so does not have compiler annotations and so cannot be instrumented by Discover. The current solution for such library function calls is to do interpositions instead. I have created Bug#20139045 against Discover to add support for these functions. In the future releases, we may have more general solutions. Stay tuned.
- Discover engineer