Bug#818178: libc6: getaddrinfo/freeadrinfo memory leak

[Tim Ruehsen <tim.ruehsen@gmx.de>]

Package: libc6
Severity: important

Dear Maintainer,

getaddrinfo/freeaddrinfo seems to have a memory leak.

Testcode:
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>

int main(void)
{
        struct addrinfo *addrinfo, hints;

        memset(&hints, 0 ,sizeof(hints));
        hints.ai_family = AF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_flags = AI_NUMERICSERV | AI_ADDRCONFIG;

        int rc;
        if ((rc = getaddrinfo("localhost", "80", &hints, &addrinfo)) == 0) {
                freeaddrinfo(addrinfo);
        }
        printf("rc=%d\n", rc);

        return 0;
}

Valgrind throws out:
==10088== HEAP SUMMARY:
==10088==     in use at exit: 28 bytes in 1 blocks
==10088==   total heap usage: 45 allocs, 44 frees, 7,337 bytes allocated
==10088== 
==10088== 28 bytes in 1 blocks are still reachable in loss record 1 of 1
==10088==    at 0x4C29C0F: malloc (vg_replace_malloc.c:299)
==10088==    by 0x4F3BA64: __res_vinit (in /lib/x86_64-linux-gnu/libc-2.22.so)
==10088==    by 0x4F3D17C: __res_maybe_init (in /lib/x86_64-linux-gnu/libc-2.22.so)
==10088==    by 0x4F09A26: gaih_inet (in /lib/x86_64-linux-gnu/libc-2.22.so)
==10088==    by 0x4F0BD0D: getaddrinfo (in /lib/x86_64-linux-gnu/libc-2.22.so)
==10088==    by 0x400625: main (in /usr/oms/src/wget2/examples/x)
==10088== 
==10088== LEAK SUMMARY:
==10088==    definitely lost: 0 bytes in 0 blocks
==10088==    indirectly lost: 0 bytes in 0 blocks
==10088==      possibly lost: 0 bytes in 0 blocks
==10088==    still reachable: 28 bytes in 1 blocks
==10088==         suppressed: 0 bytes in 0 blocks

Currently a test suite here fails due to this leak.
When setting 'addrinfo' to NULL after freeaddrinfo(), valgrind reports the leak as
'definitely lost' and returns with non-zero, thus the breakage of the test suite.

Regards, Tim


-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.4.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) (ignored: LC_ALL set to en_US.UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)