[PATCH 1/1 linux-next] netfilter: conntrack: fix kmemleak false positive

Path	csiph.com!news.mixmin.net!aioe.org!bofh.it!news.nic.it!robomod
From	Fabian Frederick <fabf@skynet.be>
Newsgroups	linux.kernel
Subject	[PATCH 1/1 linux-next] netfilter: conntrack: fix kmemleak false positive
Date	Wed, 21 Sep 2016 22:00:02 +0200
Message-ID	<sjVQu-4Lc-11@gated-at.bofh.it> (permalink)
X-Belgacom-Dynamic	yes
X-Ironport-Anti-Spam-Filtered	true
X-Ironport-Anti-Spam-Result	A2A4AwDK4+JX/yJEiNleHAEBBAEBCgEBgwI5AQEBAQEegVONM6k1gg+CBIYegWc5FAECAQEBAQEBAV4nhT4jKXEkE4hPtUaGfzGGN452BZl1j2ICj2qQYx42gkkBTAMcgVI8NIQXKoIEAQEB
X-Mailer	git-send-email 2.8.1
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	61
Organization	linux.* mail to news gateway
X-Original-Cc	Eric Dumazet <edumazet@google.com>, Pablo Neira Ayuso <pablo@netfilter.org>, linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, fabf@skynet.be
X-Original-Date	Wed, 21 Sep 2016 21:49:57 +0200
X-Original-Message-ID	<1474487397-11032-1-git-send-email-fabf@skynet.be>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1488366

Show key headers only | View raw

Since commit f330a7fdbe16
("netfilter: conntrack: get rid of conntrack timer")

closed connections remain longer in /proc/net/nf_conntrack

Running current kernel; just after boot:
cat /proc/net/nf_conntrack | wc -l = 5
4 minutes required to clean up the table.

Going back to kernel version before commit above there are
no connections after some seconds.

Referring to the commit changelog this was an expected behaviour but
it results in temporary kmemleak reports:

unreferenced object 0xffff88003b0e6600 (size 248):
  comm "rsyslogd", pid 1595, jiffies 4294741312 (age 7.343s)
  ...
  backtrace:
    [<ffffffff818f0163>] kmemleak_alloc+0x23/0x40
    [<ffffffff8117abf9>] kmem_cache_alloc+0xd9/0x180
    [<ffffffff817533a8>] __nf_conntrack_alloc.isra.50+0x48/0x170
    [<ffffffff81754262>] nf_conntrack_in+0x3a2/0x5f0
    [<ffffffff817bc9e0>] ipv4_conntrack_local+0x40/0x50
    [<ffffffff8174f17d>] nf_iterate+0x5d/0x70
    [<ffffffff8174f1ef>] nf_hook_slow+0x5f/0xb0
    [<ffffffff8176ffbd>] __ip_local_out+0xad/0xe0
    [<ffffffff81770007>] ip_local_out+0x17/0x40
    [<ffffffff817711f4>] ip_send_skb+0x14/0x40
    [<ffffffff81797591>] udp_send_skb+0x91/0x260
    [<ffffffff817985e5>] udp_sendmsg+0x2f5/0x950
    [<ffffffff817a4f80>] inet_sendmsg+0x60/0x90
    [<ffffffff816fe7d3>] sock_sendmsg+0x33/0x40
    [<ffffffff816fed0e>] SYSC_sendto+0xee/0x160
    [<ffffffff816ff719>] SyS_sendto+0x9/0x10

(248 bytes being an nf_conn structure)

Those structures being cleared in gc_worker() later on we can't talk
about unreferenced object so this patch uses kmemleak_not_leak() to
prevent those warnings.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
---
 net/netfilter/nf_conntrack_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 50106a1..59396f3 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1022,6 +1022,7 @@ __nf_conntrack_alloc(struct net *net,
 	 * SLAB_DESTROY_BY_RCU.
 	 */
 	ct = kmem_cache_alloc(nf_conntrack_cachep, gfp);
+	kmemleak_not_leak(ct);
 	if (ct == NULL)
 		goto out;
 
-- 
2.8.1

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[PATCH 1/1 linux-next] netfilter: conntrack: fix kmemleak false positive Fabian Frederick <fabf@skynet.be> - 2016-09-21 22:00 +0200
  Re: [PATCH 1/1 linux-next] netfilter: conntrack: fix kmemleak false  positive Florian Westphal <fw@strlen.de> - 2016-09-21 23:10 +0200
    Re: [PATCH 1/1 linux-next] netfilter: conntrack: fix kmemleak false  positive Fabian Frederick <fabf@skynet.be> - 2016-09-22 20:00 +0200
      Re: [PATCH 1/1 linux-next] netfilter: conntrack: fix kmemleak false  positive Florian Westphal <fw@strlen.de> - 2016-09-23 00:00 +0200

csiph-web