Re: panic on rmmod of nf_conntrack_irc

Mariusz Kozlowski
2009-04-14T20:39:23Z

On Tue, 14 Apr 2009 22:14:20 +0200
Eric Dumazet <dada1@cosmosbay.com> wrote:

> 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 ?

Bingo! Your patch fixes it. BTW this was happening for a few more modules - ebt_log, ebt_ulog, ipt_LOG,
and probably others using nf_log_register/nf_log_unregister.

> Thank you

Thanks,

Mariusz

> 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) {
>