Can you install samba-debuginfo and run with gdb instead of valgrind to get a full backtrace?

Also please post your nsswitch.conf and smb.conf.

$ grep ^hosts /etc/nsswitch.conf
hosts:      files wins dns myhostname

(gdb) bt
#0  0x41b8f8f2 in load_interfaces () at ../source3/lib/interface.c:524
#1  0xb7ba901c in nss_wins_init () at ../nsswitch/wins.c:57
#2  lookup_byname_backend (count=0xbfffd230, 
    name=0xbfffd2bc "no.such.address.") at ../nsswitch/wins.c:69
#3  _nss_wins_gethostbyname_r (
    hostname=hostname@entry=0xbfffdbe7 "no.such.address.", 
    he=he@entry=0xbfffd93c, buffer=buffer@entry=0xbfffd4b0 "\177", 
    buflen=buflen@entry=916, h_errnop=h_errnop@entry=0xb7bc9708)
    at ../nsswitch/wins.c:303
#4  0xb7ba9253 in _nss_wins_gethostbyname2_r (
    name=0xbfffdbe7 "no.such.address.", af=2, he=0xbfffd93c, 
    buffer=0xbfffd4b0 "\177", buflen=916, h_errnop=0xb7bc9708)
    at ../nsswitch/wins.c:400
#5  0x4112dd04 in __gethostbyname2_r (
    name=name@entry=0xbfffdbe7 "no.such.address.", af=af@entry=2, 
    resbuf=resbuf@entry=0xbfffd93c, buffer=0xbfffd4b0 "\177", 
    buflen=buflen@entry=916, result=0xbfffd938, 
    h_errnop=h_errnop@entry=0xbfffd934) at ../nss/getXXbyYY_r.c:255
#6  0x410f886a in gaih_inet (name=name@entry=0xbfffdbe7 "no.such.address.", 
    service=0xbfffd4b0, req=req@entry=0xbfffdaf8, pai=pai@entry=0xbfffd9e0, 
    naddrs=naddrs@entry=0xbfffd9f0) at ../sysdeps/posix/getaddrinfo.c:584
#7  0x410fb4bb in __GI_getaddrinfo (name=0xbfffdbe7 "no.such.address.", 
    service=<optimized out>, hints=0xbfffdaf8, pai=0xbfffdb18)
    at ../sysdeps/posix/getaddrinfo.c:2359
#8  0xb7c34bba in netsnmp_getaddrinfo () from snmplib/.libs/libnetsnmp.so.30
#9  0xb7c34939 in netsnmp_gethostbyname_v4 ()
   from snmplib/.libs/libnetsnmp.so.30
#10 0xb7c6dd6a in netsnmp_udp_parse_security ()
   from snmplib/.libs/libnetsnmp.so.30
#11 0xb7c39b51 in run_config_handler () from snmplib/.libs/libnetsnmp.so.30
#12 0xb7c3afd7 in read_config () from snmplib/.libs/libnetsnmp.so.30
#13 0xb7c39880 in read_config_with_type_when ()
   from snmplib/.libs/libnetsnmp.so.30
#14 0xb7c3b366 in read_configs_optional () from snmplib/.libs/libnetsnmp.so.30
#15 0xb7c3b4ef in read_configs () from snmplib/.libs/libnetsnmp.so.30
#16 0xb7c15083 in init_snmp () from snmplib/.libs/libnetsnmp.so.30
#17 0x0804b6e9 in main ()

Created attachment 700644 [details]
/etc/samba/smb.conf

This is really strange. We probe the kernel for the interfaces, then duplicate the memory with and crash when accessing an entry.

523 for (i=0;i<total_probed;i++) {                            
524     if (probed_ifaces[i].flags & IFF_BROADCAST) {

Here we crash.

Earlier we do:

total_probed = get_interfaces(talloc_tos(), ifaces);
if (total_probed > 0) {                                       
    probed_ifaces = (struct iface_struct )memdup(ifaces, sizeof(ifaces[0])*total_probed);

Maybe on your system sizeof(ifaces[0]) * total_probed results in -1095427497

Can you set a breakpoint at load_interfaces() and after line 503 print the values:

p total_probed
p ifaces[0]
p sizeof(ifaces[0])

Interface information:

$ ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:7a:8b:d3 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.102/24 brd 192.168.1.255 scope global eth0
    inet6 fe80::5054:ff:fe7a:8bd3/64 scope link 
       valid_lft forever preferred_lft forever

And the gdb output:

$ LD_LIBRARY_PATH=agent/.libs:snmplib/.libs gdb agent/.libs/snmpd
(gdb) break load_interfaces
Function "load_interfaces" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (load_interfaces) pending.
(gdb) run -Mmibs -f -d -r -U -Lo  -C -c snmpd.conf udp:127.0.0.1:8794
(gdb) Breakpoint 1, load_interfaces () at ../source3/lib/interface.c:495
495     {
(gdb) next
496             struct iface_struct *ifaces = NULL;
(gdb) next
497             const char **ptr = lp_interfaces();
(gdb) next
500             gfree_interfaces();
(gdb) print ptr
$2 = (const char **) 0x0
(gdb) next
503             total_probed = get_interfaces(talloc_tos(), &ifaces);
(gdb) next
505             if (total_probed > 0) {
(gdb) print ifaces[0]
$2 = {name = "lo", '\000' <repeats 13 times>, flags = 65609, ip = {
    ss_family = 10, __ss_align = 0, 
    __ss_padding = '\000' <repeats 15 times>, "\001", '\000' <repeats 103 times>}, netmask = {ss_family = 10, __ss_align = 0, 
    __ss_padding = "\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377\377", '\000' <repeats 103 times>}, bcast = {ss_family = 10, __ss_align = 0, 
    __ss_padding = '\000' <repeats 15 times>, "\001", '\000' <repeats 103 times>}}
(gdb) print sizeof(ifaces[0])
$3 = 404
(gdb) next
503             total_probed = get_interfaces(talloc_tos(), &ifaces);
(gdb) next
505             if (total_probed > 0) {
(gdb) next
506                     probed_ifaces = (struct iface_struct *)memdup(ifaces,
(gdb) next
508                     if (!probed_ifaces) {
(gdb) print probed_ifaces
$10 = (struct iface_struct *) 0x0
(gdb) next
506                     probed_ifaces = (struct iface_struct *)memdup(ifaces,
(gdb) next
508                     if (!probed_ifaces) {
(gdb) print probed_ifaces
$11 = (struct iface_struct *) 0xffffffff
(gdb) next
513             TALLOC_FREE(ifaces);
(gdb) next
517             if (!ptr || !*ptr || !**ptr) {
(gdb) next
513             TALLOC_FREE(ifaces);
(gdb) next
517             if (!ptr || !*ptr || !**ptr) {
(gdb) next
518                     if (total_probed <= 0) {
(gdb) next
524                             if (probed_ifaces[i].flags & IFF_BROADCAST) {
(gdb) print i
$4 = 0
(gdb) print probed_ifaces
$5 = (struct iface_struct *) 0xffffffff
(gdb) next
Program received signal SIGSEGV, Segmentation fault.
0x41b8f8f2 in load_interfaces () at ../source3/lib/interface.c:524
524                             if (probed_ifaces[i].flags & IFF_BROADCAST) {

This is really strange. I will try to reproduce it here. This is a F18 with all the latest updates?

That's correct, this has been observed on up to date F18 system. I had run "yum update -y" shortly before I ran this test.

This could be related https://bugzilla.samba.org/show_bug.cgi?id=9666

Probably the same issue as https://bugzilla.redhat.com/show_bug.cgi?id=1000780.

Candidate fix: http://sourceforge.net/p/net-snmp/mailman/message/31405941/.

*** Bug 1000780 has been marked as a duplicate of this bug. ***

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