dhcpcd-discuss

On 23/11/2020 10:48, [anp/hsw] wrote:
> Hello!
> I'm using 3.2.101 kernel and i686 (ia32) build of dhcpcd.

This is part of the problem.

> To version 7 it works normally (no segfault). But from v8 and up to
> latest git build it gets segmentation fault while trying to add IP
> address for interface.
> Here is gdb run of latest git version (ip address replaced with 192.168
> for security reason):
>
> (gdb) b if_address
> Breakpoint 1 at 0x29f0c: file if-linux.c, line 1827.
> (gdb) run
> Starting program: /tmp/dhcpcd -nBpEAKLGdd -h system -t 0 -l 3600
> -c /etc/dhcpcd/dynamic-eth0.1446 eth0.1446
> read_config: /etc/dhcpcd.conf: No such file or directory
> sending signal HUP to pid 25191
> no such user dhcpcd
> main: mkdir: /var/db/dhcpcd: No such file or directory

So dhcpcd-9 builds with privilege separation.
This requires a user to be added to your system otherwise it will be disabled.
Also, /var/db doesn't exist. dhcpcd cannot create that for you.
Either create it or adjust your configure to a different location and recompile.

> dhcpcd-9.3.3 starting
> DUID 00:04:49:43:4d:53:02:00:90:13:25:00:13:90:25:00:c4:84
> read_config: /etc/dhcpcd.conf: No such file or directory
> eth0.1446: executing: /etc/dhcpcd/dynamic-eth0.1446 PREINIT
> eth0.1446: IAID ff:00:05:a6
> eth0.1446: delaying IPv6 router solicitation for 0.9 seconds
> eth0.1446: delaying IPv4 for 1.9 seconds
> eth0.1446: soliciting an IPv6 router
> eth0.1446: sending Router Solicitation
> eth0.1446: using hwaddr 00:a0:d1:cf:de:34
> eth0.1446: reading lease: /var/db/dhcpcd/eth0.1446.lease
> eth0.1446: soliciting a DHCP lease
> eth0.1446: sending DISCOVER (xid 0x93d1fc8c), next in 3.8 seconds
> eth0.1446: offered 192.168.168.51 from 80.89.133.227
> eth0.1446: sending REQUEST (xid 0x93d1fc8c), next in 3.1 seconds
> eth0.1446: acknowledged 192.168.168.51 from 80.89.133.227
> eth0.1446: leased 192.168.168.51 for 3600 seconds
> eth0.1446: renew in 1800 seconds, rebind in 3150 seconds
> eth0.1446: writing lease: /var/db/dhcpcd/eth0.1446.lease
> dhcp_writefile: /var/db/dhcpcd/eth0.1446.lease: No such file or
> directory
> eth0.1446: adding IP address 192.168.168.51/24 broadcast 192.168.168.255
>   
> Breakpoint 1, if_address (cmd=20 '\024', ia=0x800acc48) at
> if-linux.c:1827
> 1827    {
> (gdb) info locals
> nlm = {hdr = {nlmsg_len = 8, nlmsg_type = 80, nlmsg_flags = 0, nlmsg_seq
> = 2426816512, nlmsg_pid = 3085056288}, ifa = {ifa_family = 56 '8',
> ifa_prefixlen = 93 ']', ifa_flags = 7 '\a',

This is the second part of the problem.
Your kernel headers are vastly newer than the kernel.
IFA_F_NOPREFIXROUTE was first defined in Linux-3.13 but your running kernel is 
Linux-3.2
Essentially using newer headers advertises features which are not available, and 
this is what you are seeing.


>      ifa_scope = 128 '', ifa_index = 3221212584},
>    buffer = "n.\001\a\000\000\000lM\006╢мЪ©мЪ©\030\000\000\000TNЭ╥╦мЪ©lM
> \006 9Б╥\022\000\000\000╢мЪ©\000H╕Ш\000\000\000E\000\000\000\030нЪ©"}
> cinfo = {ifa_prefered = 0, ifa_valid = 91, cstamp = 0, tstamp = 57}
> retval = 0
> flags = 110
> (gdb) c
> Continuing.
> ipv4_addaddr: if_addaddress: Invalid argument
>
> Program received signal SIGSEGV, Segmentation fault.
> 0x8002ef75 in dhcp_openudp (ia=0x8) at dhcp.c:1604
> 1604                    sin.sin_addr = *ia;
> (gdb) print *ia
> Cannot access memory at address 0x8
> (gdb) print ia
> $1 = (struct in_addr *) 0x8
> (gdb) info locals
> s = 16
> sin = {sin_family = 2, sin_port = 17408, sin_addr = {s_addr = 0},
> sin_zero = "\000\000\000\000\000\000\000"}
> n = 1
> (gdb) quit
>
> I can try to get more info, it it will be helpful.

Irregardless of the above, dhcpcd should still not crash.
A backtrace here would be helpful.

Roy