netdev - [PATCH 1/2] netfilter: nf_ct_dccp/sctp: fix memory leak after netns cleanup

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Message-Id: <1499345665-7428-2-git-send-email-pablo@netfilter.org>
Date:   Thu,  6 Jul 2017 14:54:24 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 1/2] netfilter: nf_ct_dccp/sctp: fix memory leak after netns cleanup

From: Liping Zhang <zlpnobody@...il.com>

After running the following commands for a while, kmemleak reported that
"1879 new suspected memory leaks" happened:
  # while : ; do
  ip netns add test
  ip netns delete test
  done

  unreferenced object 0xffff88006342fa38 (size 1024):
  comm "ip", pid 15477, jiffies 4295982857 (age 957.836s)
  hex dump (first 32 bytes):
    b8 b0 4d a0 ff ff ff ff c0 34 c3 59 00 88 ff ff  ..M......4.Y....
    04 00 00 00 a4 01 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff8190510a>] kmemleak_alloc+0x4a/0xa0
    [<ffffffff81284130>] __kmalloc_track_caller+0x150/0x300
    [<ffffffff812302d0>] kmemdup+0x20/0x50
    [<ffffffffa04d598a>] dccp_init_net+0x8a/0x160 [nf_conntrack]
    [<ffffffffa04cf9f5>] nf_ct_l4proto_pernet_register_one+0x25/0x90
  ...
  unreferenced object 0xffff88006342da58 (size 1024):
  comm "ip", pid 15477, jiffies 4295982857 (age 957.836s)
  hex dump (first 32 bytes):
    10 b3 4d a0 ff ff ff ff 04 35 c3 59 00 88 ff ff  ..M......5.Y....
    04 00 00 00 a4 01 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff8190510a>] kmemleak_alloc+0x4a/0xa0
    [<ffffffff81284130>] __kmalloc_track_caller+0x150/0x300
    [<ffffffff812302d0>] kmemdup+0x20/0x50
    [<ffffffffa04d6a9d>] sctp_init_net+0x5d/0x130 [nf_conntrack]
    [<ffffffffa04cf9f5>] nf_ct_l4proto_pernet_register_one+0x25/0x90
  ...

This is because we forgot to implement the get_net_proto for sctp and
dccp, so we won't invoke the nf_ct_unregister_sysctl to free the
ctl_table when do netns cleanup. Also note, we will fail to register
the sysctl for dccp/sctp either due to the lack of get_net_proto.

Fixes: c51d39010a1b ("netfilter: conntrack: built-in support for DCCP")
Fixes: a85406afeb3e ("netfilter: conntrack: built-in support for SCTP")
Cc: Davide Caratti <dcaratti@...hat.com>
Signed-off-by: Liping Zhang <zlpnobody@...il.com>
Acked-by: Davide Caratti <dcaratti@...hat.com>
Acked-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_conntrack_proto_dccp.c | 7 +++++++
 net/netfilter/nf_conntrack_proto_sctp.c | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/net/netfilter/nf_conntrack_proto_dccp.c b/net/netfilter/nf_conntrack_proto_dccp.c
index b553fdd68816..4707d997558a 100644
--- a/net/netfilter/nf_conntrack_proto_dccp.c
+++ b/net/netfilter/nf_conntrack_proto_dccp.c
@@ -872,6 +872,11 @@ static int dccp_init_net(struct net *net, u_int16_t proto)
 	return dccp_kmemdup_sysctl_table(net, pn, dn);
 }
 
+static struct nf_proto_net *dccp_get_net_proto(struct net *net)
+{
+	return &net->ct.nf_ct_proto.dccp.pn;
+}
+
 struct nf_conntrack_l4proto nf_conntrack_l4proto_dccp4 __read_mostly = {
 	.l3proto		= AF_INET,
 	.l4proto		= IPPROTO_DCCP,
@@ -904,6 +909,7 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_dccp4 __read_mostly = {
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= dccp_init_net,
+	.get_net_proto		= dccp_get_net_proto,
 };
 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_dccp4);
 
@@ -939,5 +945,6 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_dccp6 __read_mostly = {
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= dccp_init_net,
+	.get_net_proto		= dccp_get_net_proto,
 };
 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_dccp6);
diff --git a/net/netfilter/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c
index 1c5b14a6cab3..4ed976f137d3 100644
--- a/net/netfilter/nf_conntrack_proto_sctp.c
+++ b/net/netfilter/nf_conntrack_proto_sctp.c
@@ -786,6 +786,11 @@ static int sctp_init_net(struct net *net, u_int16_t proto)
 	return sctp_kmemdup_sysctl_table(pn, sn);
 }
 
+static struct nf_proto_net *sctp_get_net_proto(struct net *net)
+{
+	return &net->ct.nf_ct_proto.sctp.pn;
+}
+
 struct nf_conntrack_l4proto nf_conntrack_l4proto_sctp4 __read_mostly = {
 	.l3proto		= PF_INET,
 	.l4proto 		= IPPROTO_SCTP,
@@ -819,6 +824,7 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_sctp4 __read_mostly = {
 	},
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 	.init_net		= sctp_init_net,
+	.get_net_proto		= sctp_get_net_proto,
 };
 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_sctp4);
 
@@ -855,5 +861,6 @@ struct nf_conntrack_l4proto nf_conntrack_l4proto_sctp6 __read_mostly = {
 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 #endif
 	.init_net		= sctp_init_net,
+	.get_net_proto		= sctp_get_net_proto,
 };
 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_sctp6);
-- 
2.1.4