Hi. Try to assemble uClibc and bird with debug symbols, and try to analyze core dump. Also it'll be good to run bird (better- to use debug version) in valgrind - it'll show all suspicious cases (like access across array borders, use of uninitialized variables and so on). On 24.10.2018 18:05, Alexander Velkov wrote:

Hello bird-team,

I have a bird v1.6.4. configuration that works fine. A certain set of actions leads to a segfault and a crash of the bird binary.

I have configured and built bird 1.6.4. with IPv6 support that runs on a box with a i686 linux with kernel v4.14.75. My bird configuration:

### bird6.conf:

protocol device {   scan time 10; }

protocol direct C_main {   interface "*";   preference 255;   check link; }

protocol kernel K_main {   preference 255;   scan time 20;   export all;   learn; }

include "*.conff";

### ospfv3.conff in the same directory:

debug protocols all; log syslog { info, remote, warning, error, auth, fatal, bug };

protocol ospf O_main {   preference 145;   instance id 0;

  area 172.16.0.0 {

    interface "vti0" {       dead 120;       hello 30;       cost 1;       priority 1;       type pointopoint;

      neighbors {         fe80::e68:3ff:fe26:5130;       };     };

    interface "eth1" {       dead 40;       hello 10;       cost 1;       priority 1;       type broadcast;       stub yes;     };   };

  import filter {     accept;   };   export filter {     reject;   }; }

### The following actions lead to a crash of bird6:

EEPD[~]# /sbin/bird6 -P /var/run/bird6.pid -c /var/etc/bird6/bird6.conf

Oct 24 14:23:08 EEPD info  bird6   [ 4684]: Started

EEPD[~]# ps | grep bird6  4930 root      1500 S    /sbin/bird6 -P /var/run/bird6.pid -c /var/etc/bird6/bird6.conf  4932 root      1284 S    grep bird6

EEPD[~]# EEPD[~]# ip -6 link add vti0 type vti6 local fd00::38 remote fd00::1b ikey 2 okey 2; EEPD[~]# ip -6 link set vti0 up; EEPD[~]# ifconfig vti0 mtu 1422

Oct 24 14:23:17 EEPD err   bird6   [ 4684]: KIF: Received address message for unknown interface 33 Oct 24 14:23:20 EEPD err   bird6   [ 4684]: O_main: Socket error on vti0: Invalid argument Oct 24 14:23:20 EEPD info  kernel: [ 4684]: segfault at 58e ip b7eed103 sp bf9acad8 error 4 in libuClibc-1.0.30.so <http://libuClibc-1.0.30.so>[b7ebd000+72000]

EEPD[~]# EEPD[~]# ps | grep bird6  4988 root      1284 S    grep bird6 EEPD[~]#

### Further testing

- bird does NOT crash if the contents of bird6.conf and ospfv3.conf are placed in a single file without inclusion. - bird does NOT crash if the call 'ifconfig vti0 mtu 1422' is executed before 'ip -6 link set vti0 up'.

Hope this information helps.

Best Regards Alex