Re: ifconfig dumps core and gdb uses an undefined symbol

On Wed, 14 Jun 2023 09:09:04 +0100
Alexander Chernikov <melifaro@FreeBSD.org> wrote:

> > On 14 Jun 2023, at 08:59, Gary Jennejohn <garyj@gmx.de> wrote:
> Hi Gary,
> >
> > So, now I have a new problem with current.
> >
> > I just now updated my current sources and ran buildworld and buildkernel,
> > since Gleb fixed the WITHOUT_PF problem.
> >
> > After installing the new world and kernel I see that ifconfig is dumping
> > a core, apparently when it tries to show lo0, since re0 is correctly
> > shown:
> >
> > ifconfig
> > re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 4088 options=82098<VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC,LINKSTATE>
> >       ether redacted
> >       inet 192.168.178.XXX netmask 0xffffff00 broadcast 192.168.178.255
> > Segmentation fault (core dumped)
> Could you please try to narrow down the crashing command? e.g.
> Ifconfig lo0
> Ifconfig lo0 net
> Ifconfig lo0 inet6
> Could you try to rebuild ifconfig w/o netlink (e.g. set WITHOUT_NETLINK=yes in the make.conf & make -C sbin/ifconfig clean all install) and see if the new binary works?
>

I already have WITHOUT_NETLINK=yes in my /etc/src.conf.

I didn't install ifconfig. I simply started it from the build directory.

ifconfig lo0 shows the settings for lo0 and then dumps core.

> >
> > Unfortunately, I see this error message when I try to look at the core
> > file with gdb:
> >
> > gdb /sbin/ifconfig ifconfig.core
> > ld-elf.so.1: Undefined symbol "rl_eof_found" referenced from COPY
> > relocation in /usr/local/bin/gdb
> Not a specialist here, but if you could build the binary with debug
> (make DEBUG_FLAGS=-O0 -g3 sbin/ifconfig clean all install) & share the
> binary & core with me, I could take a look on what?s happening.
> >

I compiled gbd under /usr/ports and it now works, although it's emitting
some weird errors.

-O0 -g3 removes too much and gdb shows no useful information.

With just -g3 I get this output from gdb after running the newly compiled
ifconfig:

Program terminated with signal SIGSEGV, Segmentation fault
warning: Section `.reg-xstate/100294' in core file too small.
#0  lagg_status (ctx=0x2f051660ba00) at /usr/src/sbin/ifconfig/iflagg.c:223
223             const int verbose = ctx->args->verbose;
(gdb) bt
#0  lagg_status (ctx=0x2f051660ba00) at /usr/src/sbin/ifconfig/iflagg.c:223
#1  0x00002efcf610ea55 in af_other_status (ctx=0x2f051660ba00)
    at /usr/src/sbin/ifconfig/ifconfig.c:964
#2  status (args=0x2f051660ba70, ifa=0x2f051a2f2000, sdl=<optimized out>)
    at /usr/src/sbin/ifconfig/ifconfig.c:1788
#3  list_interfaces_ioctl (args=0x2f051660ba70)
    at /usr/src/sbin/ifconfig/ifconfig.c:845
#4  list_interfaces (args=0x2f051660ba70)
    at /usr/src/sbin/ifconfig/ifconfig.c:428
#5  main (ac=<optimized out>, av=<optimized out>)
    at /usr/src/sbin/ifconfig/ifconfig.c:724
(gdb)

I looked at ctx:

(gdb) p ctx
$1 = (if_ctx *) 0x2f051660ba00
(gdb) p/x *0x2f051660ba00
$2 = 0x0 <==
(gdb)

So, looks like the problem is in iflagg and ctx is NULL.

--
Gary Jennejohn