ax25 kernel problem sometimes accur

From: Tihomir Heidelberg (chjm@mail.dy.fi)
Date: Wed Dec 04 2002 - 09:21:29 EET

  • Next message: Sandor Dibuz: "Re: ax25 kernel problem sometimes accur"

    Hi

    After few days of running 9a0tcp gateway, ax25 kernel at
    9a0tcp get broken. When the problem occur, all connections
    are running well, so I think that ax25_list is not broken
    because ax25_find_socket and ax25_find_cb functions are doing
    good work, but running netstat or cat /proc/net/ax25 will
    do "segementation fault". This makes big problems to some
    of my applications.

    The problem occur on kernels 2.4.18, 2.4.19 and 2.4.20, but
    I notice it only on 9a0tcp gateway, even am running it on
    several machines. Maybe, because 9a0tcp have few times more
    traffic.

    I analyzed the kernel ax25 source, and I tried to find what
    can make ax25_get_info function crash. I don't know much
    about how kernel and sockets exactly work, but want to know
    if someone have the same problem, and maybe one of kernel
    guru will catch a problem.

    But, what I suspect, in af_ax25.c we define a destructor for
    our sockets:
             sk->destruct = ax25_free_sock;
    I guess that somebody/sometimes call this destructor when
    destroying a socket. I think that after that, socket cannot be
    considered as valid, but as control block still exists,
    shouldn't we set sk in control block to NULL ? ax25_get_info
    will still find that control block with sk set to destroyed
    socket, isn't it ?
    I added to the end of ax25_free_sock function this line:
            sk->protinfo.ax25->sk=NULL;
    and I am waiting to see if this will help.
    Is there any expert that can tell me whats wrong here.

    Many thanks,

    73 de Tihomir Heidelberg, cqrlu.fpcfsm@roskapostia.tunk.net
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