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    SubjectRe: panic on rmmod of nf_conntrack_irc
    Mariusz Kozlowski a écrit :
    > On Tue, 14 Apr 2009 14:16:37 +0200
    > Patrick McHardy <kaber@trash.net> wrote:
    >
    >> Eric Dumazet wrote:
    >>> Patrick McHardy a écrit :
    >>>> Mariusz Kozlowski wrote:
    >>>>> netfilter: nf_conntrack: use SLAB_DESTROY_BY_RCU and get rid of
    >>>>> call_rcu()
    >>>> Thanks for the report. Does this patch fix it?
    >>>>
    >>> Hi Patrick, sorry for the delay, I was in holidays.
    >> No problem, me too :)
    >>
    >>> I should have used different fields names (from "next", "first", ...) to catch this
    >>> kind of errors at compile time :(
    >> >
    >>> Something like :
    >> Thanks Eric. I guess at this point it doesn't really matter anymore
    >> for the upstream kernel, but I'll apply your patch after getting
    >> confirmation from Mariusz to make sure that people maintaining
    >> external patches will notice the change (and won't send me broken
    >> patches :)).
    >
    > Ok good. It doesn't panic now on nf_conntrack_irc rmmod but I found another bug.
    > Now it's NULL pointer dereference I when doing rmmod of ebt_log. To reproduce simply:
    >
    > # modprobe ebt_log && rmmod ebt_log
    >
    > This is from the mainline kernel + your (Erics) patch:
    >
    > BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
    > IP: [<ffffffff8048490a>] nf_log_unregister+0x2a/0x90
    > PGD 6f0e8067 PUD 6a2e0067 PMD 0
    > Oops: 0002 [#1] PREEMPT SMP
    > last sysfs file: /sys/devices/LNXSYSTM:00/device:00/PNP0A08:00/device:01/PNP0C09:00/PNP0C0A:00/power_supply/BAT0/energy_full
    > CPU 0
    > Modules linked in: ebt_log(-) nfs lockd auth_rpcgss sunrpc netconsole af_packet i915 drm i2c_algo_bit i2c_core kvm_intel kvm ppdev acpi_cpufreq cpufreq_stats cpufreq_powersave cpufreq_userspace cpufreq_conservative cpufreq_ondemand freq_table fan sbs sbshc container pci_slot iptable_filter ip_tables x_tables sbp2 lp fuse snd_hda_codec_analog arc4 ecb snd_hda_intel snd_hda_codec snd_pcm_oss snd_mixer_oss iwl3945 iwlcore thinkpad_acpi sr_mod cdrom pcmcia mac80211 snd_pcm rfkill led_class snd_seq_dummy snd_seq_oss snd_seq_midi_event evdev thermal uhci_hcd ehci_hcd parport_pc ohci1394 nvram yenta_socket rsrc_nonstatic pcmcia_core snd_seq pcspkr psmouse serio_raw usbcore cfg80211 e1000e ieee1394 sg parport battery ac button processor snd_timer snd_seq_device intel_agp snd soundcore snd_page_alloc
    > Pid: 10249, comm: rmmod Not tainted 2.6.30-rc1-00204-gb0cbc86-dirty #33 7667Y24
    > RIP: 0010:[<ffffffff8048490a>] [<ffffffff8048490a>] nf_log_unregister+0x2a/0x90
    > RSP: 0018:ffff88006a331ec8 EFLAGS: 00010207
    > RAX: 0000000000000000 RBX: ffffffffa02d1d00 RCX: 0000000000000000
    > RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffffffff8065bb80
    > RBP: ffff88006a331ed8 R08: 0000000000000002 R09: ffffffff80676600
    > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
    > R13: 0000000000000880 R14: 0000000000000000 R15: 0000000000000000
    > FS: 0000000000000000(0000) GS:ffff880001010000(0063) knlGS:00000000f7fc46b0
    > CS: 0010 DS: 002b ES: 002b CR0: 000000008005003b
    > CR2: 0000000000000008 CR3: 000000006f9f9000 CR4: 00000000000026a0
    > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
    > Process rmmod (pid: 10249, threadinfo ffff88006a330000, task ffff88006f3c8000)
    > Stack:
    > ffffffffa02d1e80 ffffffffa02d1e80 ffff88006a331ee8 ffffffffa02d1518
    > ffff88006a331f78 ffffffff8026ddbb 00676f6c5f746265 ffffffff80229e77
    > 0000000000000282 ffff88006a331f58 ffff88006f3c8000 0000000000000000
    > Call Trace:
    > [<ffffffffa02d1518>] ebt_log_fini+0x10/0x1e [ebt_log]
    > [<ffffffff8026ddbb>] sys_delete_module+0x18b/0x240
    > [<ffffffff80229e77>] ? do_page_fault+0x187/0x2a0
    > [<ffffffff8022f08b>] sysenter_dispatch+0x7/0x32
    > Code: 90 55 48 89 e5 53 48 89 fb 48 83 ec 08 48 c7 c7 80 bb 65 80 e8 78 a9 06 00 31 c9 eb 31 0f 1f 40 00 48 8b 54 4b 18 48 8b 44 4b 20 <48> 89 42 08 48 89 10 48 c7 44 4b 20 00 02 20 00 48 c7 44 4b 18
    > RIP [<ffffffff8048490a>] nf_log_unregister+0x2a/0x90
    > RSP <ffff88006a331ec8>
    > CR2: 0000000000000008
    >
    > If this is not related or you don't have a clue I can bisect it.
    >

    Thanks a lot for this report Mariusz

    Not related to my RCU patch IMHO (as it only touches conntrack)

    Check commit ca735b3aaa945626ba65a3e51145bfe4ecd9e222

    netfilter: use a linked list of loggers

    This patch modifies nf_log to use a linked list of loggers for each
    protocol. This list of loggers is read and write protected with a
    mutex.

    This patch separates registration and binding. To be used as
    logging module, a module has to register calling nf_log_register()
    and to bind to a protocol it has to call nf_log_bind_pf().
    This patch also converts the logging modules to the new API. For nfnetlink_log,
    it simply switchs call to register functions to call to bind function and
    adds a call to nf_log_register() during init. For other modules, it just
    remove a const flag from the logger structure and replace it with a
    __read_mostly.

    Signed-off-by: Eric Leblond <eric@inl.fr>
    Signed-off-by: Patrick McHardy <kaber@trash.net>

    It seems "struct list_head list[NFPROTO_NUMPROTO];" is not initialized in "struct nf_logger" ?

    Please try following patch ?

    Thank you

    diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
    index 8bb998f..d8b85ab 100644
    --- a/net/netfilter/nf_log.c
    +++ b/net/netfilter/nf_log.c
    @@ -36,10 +36,14 @@ static struct nf_logger *__find_logger(int pf, const char *str_logger)
    int nf_log_register(u_int8_t pf, struct nf_logger *logger)
    {
    const struct nf_logger *llog;
    + int i;

    if (pf >= ARRAY_SIZE(nf_loggers))
    return -EINVAL;

    + for (i = 0; i < NFPROTO_NUMPROTO; i++)
    + INIT_LIST_HEAD(&logger->list[i]);
    +
    mutex_lock(&nf_log_mutex);

    if (pf == NFPROTO_UNSPEC) {
    --
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