From: Patrick McHardy <kaber@trash.net>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, David Miller <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Pablo Neira Ayuso <pablo@netfilter.org>
Subject: Re: [bug] __nf_ct_refresh_acct(): WARNING: at lib/list_debug.c:30 __list_add+0x7d/0xad()
Date: Thu, 18 Jun 2009 18:09:48 +0200 [thread overview]
Message-ID: <4A3A66CC.4090205@trash.net> (raw)
In-Reply-To: <4A3A6143.3040607@gmail.com>
Eric Dumazet wrote:
> In my own analysis, I found death_by_timeout() might be problematic,
> with RCU and lockless lookups.
>
> static void death_by_timeout(unsigned long ul_conntrack)
> {
> struct nf_conn *ct = (void *)ul_conntrack;
>
> if (!test_bit(IPS_DYING_BIT, &ct->status) &&
> unlikely(nf_conntrack_event(IPCT_DESTROY, ct) < 0)) {
> /* destroy event was not delivered */
> nf_ct_delete_from_lists(ct);
> << HERE >>
>
> nf_ct_insert_dying_list(ct);
> return;
> }
> set_bit(IPS_DYING_BIT, &ct->status);
> nf_ct_delete_from_lists(ct);
> nf_ct_put(ct);
> }
>
>
> We delete ct from a list and insert it in a new list.
>
> I believe a reader could "*catch*" ct while doing a lookup and miss the end
> of its chain. (nulls algo check the null value at the end of lookup and can
> decide to restart the lookup if the null value is not the expected one)
>
> We need to change nf_conntrack_init_net() and use a different "null" value,
> guaranteed not being used in regular lists
Good catch. This is a new bug, but it shouldn't matter in this case
since nf_conntrack_event() can't fail unless you have a userspace
listener that makes use of reliable delivery, which I think hasn't
even been released yet.
> Patch follows :
Looks good. If you send me a Signed-off-by: I'll already apply it.
next prev parent reply other threads:[~2009-06-18 16:09 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-15 12:04 [GIT]: Networking David Miller
2009-06-16 9:15 ` Ingo Molnar
2009-06-16 9:19 ` David Miller
2009-06-16 9:33 ` Ingo Molnar
2009-06-16 9:44 ` Ingo Molnar
2009-06-16 9:44 ` Alan Cox
2009-06-16 9:48 ` Ingo Molnar
2009-06-16 9:56 ` David Miller
2009-06-16 10:11 ` Ingo Molnar
2009-06-16 10:35 ` David Miller
2009-06-16 13:38 ` Eric Dumazet
2009-06-16 14:19 ` Eric Dumazet
2009-06-16 18:59 ` Linus Torvalds
2009-06-16 19:08 ` David Miller
2009-06-16 19:37 ` Eric Dumazet
2009-06-16 20:12 ` Eric Dumazet
2009-06-17 6:41 ` [PATCH] net: correct off-by-one write allocations reports Eric Dumazet
2009-06-17 11:31 ` [PATCH] atm: sk_wmem_alloc initial value is one Eric Dumazet
2009-06-18 2:06 ` David Miller
2009-06-18 2:05 ` [PATCH] net: correct off-by-one write allocations reports David Miller
2009-06-17 11:32 ` [GIT]: Networking David Miller
2009-06-16 9:21 ` David Miller
2009-06-16 9:26 ` Ingo Molnar
2009-06-16 10:47 ` David Miller
2009-06-16 10:53 ` Ingo Molnar
2009-06-16 12:24 ` Ingo Molnar
2009-06-16 12:39 ` David Miller
2009-06-17 9:21 ` [bug] __nf_ct_refresh_acct(): WARNING: at lib/list_debug.c:30 __list_add+0x7d/0xad() Ingo Molnar
2009-06-17 10:18 ` Eric Dumazet
2009-06-17 11:08 ` Ingo Molnar
2009-06-17 11:35 ` David Miller
2009-06-18 5:23 ` Ingo Molnar
2009-06-18 5:58 ` Eric Dumazet
2009-06-18 9:47 ` Patrick McHardy
2009-06-18 14:56 ` Patrick McHardy
2009-06-18 15:46 ` Eric Dumazet
2009-06-18 16:09 ` Patrick McHardy [this message]
2009-06-18 16:13 ` Pablo Neira Ayuso
2009-06-18 22:46 ` [PATCH] netfilter: conntrack: death_by_timeout() fix Eric Dumazet
2009-06-19 11:15 ` Patrick McHardy
2009-06-20 15:47 ` [bug] __nf_ct_refresh_acct(): WARNING: at lib/list_debug.c:30 __list_add+0x7d/0xad() Ingo Molnar
2009-06-20 15:56 ` Patrick McHardy
2009-06-17 11:38 ` Patrick McHardy
2009-06-17 11:51 ` Patrick McHardy
2009-06-17 11:55 ` Eric Dumazet
2009-06-17 12:00 ` Patrick McHardy
2009-06-17 12:33 ` Eric Dumazet
2009-06-17 12:36 ` Patrick McHardy
2009-06-17 13:27 ` Eric Dumazet
2009-06-17 13:29 ` Patrick McHardy
2009-06-17 14:23 ` Patrick McHardy
2009-06-17 15:29 ` Eric Dumazet
2009-06-17 15:34 ` Patrick McHardy
2009-06-18 23:18 ` [GIT]: Networking Tilman Schmidt
2009-06-19 3:36 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4A3A66CC.4090205@trash.net \
--to=kaber@trash.net \
--cc=akpm@linux-foundation.org \
--cc=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=netdev@vger.kernel.org \
--cc=pablo@netfilter.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).