Re: libiptc ... and matches , seg fault

[primero <primero@fastwebnet.it>]

Tomáš Macek wrote:

> Where points the me->version just before the step into the strcmp()?
> What this pointer contains?
>

each libipt_MATCH has to call a register_match() in his init function 
passing an "iptables_match" structure has argument that is referred as 
"me" inside the register_match function.

in my particular case me->version is equal to IPTABLES_VERSION (check 
out the libipt_tcp.c).

what could give such seg fault in a strcmp ?

bye
Francesco

> On Thu, 14 Jul 2005, Francesco Ciocchetti wrote:
>
>> Hi all ML.
>>
>> I'm tryng to develop a small apps with libiptc copyng as much as
>> possible from iptables.c
>>
>> i'm getting a segmentation fault when i call find_match with 'tcp' as
>> argument.
>>
>> searching with gdb i found that :
>>
>> my segfault arrives when in register_match
>>
>> if (strcmp(me->version, program_version) != 0) (line 1052 of iptables.c
>> 1.2.11)
>>
>> Program received signal SIGSEGV, Segmentation fault.
>> 0x0ff0b824 in strcmp () from /lib/tls/libc.so.6
>> (gdb) where
>> #0 0x0ff0b824 in strcmp () from /lib/tls/libc.so.6
>> #1 0x100083e8 in register_match ()
>> #2 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #3 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #4 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #5 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #6 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #7 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #8 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #9 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #10 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #11 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #12 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #13 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #14 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #15 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #16 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #17 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #18 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #19 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> #20 0x0fe53584 in _init () from /lib/iptables/libipt_tcp.so
>> Previous frame inner to this frame (corrupt stack?)
>>
>> If i missed some info don't esiatate to ask :)
>>
>> anyone has some hints?
>>
>> thx
>> Francesco
>>
>>
>>
>>
>>
>>
>>
>