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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 6/9] netfilter: ctnetlink: skip dumping expect when nfct_help(ct) is NULL
Date: Fri, 14 Apr 2017 02:26:48 +0200
Message-ID: <1492129611-29336-7-git-send-email-pablo@netfilter.org> (raw)
In-Reply-To: <1492129611-29336-1-git-send-email-pablo@netfilter.org>

From: Liping Zhang <zlpnobody@gmail.com>

For IPCTNL_MSG_EXP_GET, if the CTA_EXPECT_MASTER attr is specified, then
the NLM_F_DUMP request will dump the expectations related to this
connection tracking.

But we forget to check whether the conntrack has nf_conn_help or not,
so if nfct_help(ct) is NULL, oops will happen:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
 IP: ctnetlink_exp_ct_dump_table+0xf9/0x1e0 [nf_conntrack_netlink]
 Call Trace:
  ? ctnetlink_exp_ct_dump_table+0x75/0x1e0 [nf_conntrack_netlink]
  netlink_dump+0x124/0x2a0
  __netlink_dump_start+0x161/0x190
  ctnetlink_dump_exp_ct+0x16c/0x1bc [nf_conntrack_netlink]
  ? ctnetlink_exp_fill_info.constprop.33+0xf0/0xf0 [nf_conntrack_netlink]
  ? ctnetlink_glue_seqadj+0x20/0x20 [nf_conntrack_netlink]
  ctnetlink_get_expect+0x32e/0x370 [nf_conntrack_netlink]
  ? debug_lockdep_rcu_enabled+0x1d/0x20
  nfnetlink_rcv_msg+0x60a/0x6a9 [nfnetlink]
  ? nfnetlink_rcv_msg+0x1b9/0x6a9 [nfnetlink]
  [...]

Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_conntrack_netlink.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index f9c643bc1a8e..f78eadba343d 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -2794,6 +2794,12 @@ static int ctnetlink_dump_exp_ct(struct net *net, struct sock *ctnl,
 		return -ENOENT;
 
 	ct = nf_ct_tuplehash_to_ctrack(h);
+	/* No expectation linked to this connection tracking. */
+	if (!nfct_help(ct)) {
+		nf_ct_put(ct);
+		return 0;
+	}
+
 	c.data = ct;
 
 	err = netlink_dump_start(ctnl, skb, nlh, &c);
-- 
2.1.4

  parent reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-14  0:26 [PATCH 0/9] Netfilter fixes for net Pablo Neira Ayuso
2017-04-14  0:26 ` [PATCH 1/9] netfilter: xt_TCPMSS: add more sanity tests on tcph->doff Pablo Neira Ayuso
2017-04-14  0:26 ` [PATCH 2/9] netfilter: ctnetlink: using bit to represent the ct event Pablo Neira Ayuso
2017-04-14  0:26 ` [PATCH 3/9] netfilter: helper: Add the rcu lock when call __nf_conntrack_helper_find Pablo Neira Ayuso
2017-04-14  0:26 ` [PATCH 4/9] netfilter: ctnetlink: make it safer when checking the ct helper name Pablo Neira Ayuso
2017-04-14  0:26 ` [PATCH 5/9] netfilter: make it safer during the inet6_dev->addr_list traversal Pablo Neira Ayuso
2017-04-14  0:26 ` Pablo Neira Ayuso [this message]
2017-04-14  0:26 ` [PATCH 7/9] netfilter: nf_ct_expect: use proper RCU list traversal/update APIs Pablo Neira Ayuso
2017-04-14  0:26 ` [PATCH 8/9] netfilter: nft_hash: do not dump the auto generated seed Pablo Neira Ayuso
2017-04-14  0:26 ` [PATCH 9/9] netfilter: ipt_CLUSTERIP: Fix wrong conntrack netns refcnt usage Pablo Neira Ayuso
2017-04-14 14:59 ` [PATCH 0/9] Netfilter fixes for net David Miller

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