This bug has been reproduced on RHEL4, RHEL5 and F10.

Steps to reproduce this issue:

Add a an entry begining with the "+" sympbol in /etc/passwd:

# grep ^+ /etc/passwd
+bar:x:65534:100::/local/bar:/bin/bash

Change nsswitch to use compat for passwd:

# grep compat /etc/nsswitch.conf
#      compat                  Use NIS on compat mode
passwd:    compat

Compile this test:

# cat memleak_repro.c
#include <sys/types.h>
#include <pwd.h>
int main()
{
 uid_t myid = 800120545;
 getpwuid( myid );
 return(0);
}

# gcc -g -o memleak_repro memleak_repro.c

Run it under Valgrind:

# /local/opt/twwgs/valgrind323/bin/valgrind --leak-check=full ./memleak_repro

==18634== Memcheck, a memory error detector.
==18634== Copyright (C) 2002-2007, and GNU GPL'd, by Julian Seward et al.
==18634== Using LibVEX rev 1732, a library for dynamic binary translation.
==18634== Copyright (C) 2004-2007, and GNU GPL'd, by OpenWorks LLP.
==18634== Using valgrind-3.2.3, a dynamic binary instrumentation framework.
==18634== Copyright (C) 2000-2007, and GNU GPL'd, by Julian Seward et al.
==18634== For more details, rerun with: -v
==18634==
==18634==
==18634== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 9 from 4)
==18634== malloc/free: in use at exit: 292 bytes in 11 blocks.
==18634== malloc/free: 84 allocs, 73 frees, 27,827 bytes allocated.
==18634== For counts of detected errors, rerun with: -v
==18634== searching for pointers to 11 not-freed blocks.
==18634== checked 62,848 bytes.
==18634==
==18634== 292 (52 direct, 240 indirect) bytes in 1 blocks are definitely lost in loss record 1 of 3
==18634==    at 0x4904D9E: malloc (vg_replace_malloc.c:149)
==18634==    by 0x33AF1D65BE: nss_parse_service_list (in /lib64/tls/libc-2.3.4.so)
==18634==    by 0x33AF1D6C8C: __nss_database_lookup (in /lib64/tls/libc-2.3.4.so)
==18634==    by 0x4B1853A: ???
==18634==    by 0x33AF18EE9D: getpwuid_r@@GLIBC_2.2.5 (in /lib64/tls/libc-2.3.4.so)
==18634==    by 0x33AF18E7FC: getpwuid (in /lib64/tls/libc-2.3.4.so)
==18634==    by 0x4004BE: main (memleak_repro.c:6)
==18634==
==18634== LEAK SUMMARY:
==18634==    definitely lost: 52 bytes in 1 blocks.
==18634==    indirectly lost: 240 bytes in 10 blocks.
==18634==      possibly lost: 0 bytes in 0 blocks.
==18634==    still reachable: 0 bytes in 0 blocks.
==18634==        suppressed: 0 bytes in 0 blocks.