From 207df81501021f6d1a935cebf8e1f34d6d25564b Mon Sep 17 00:00:00 2001 From: Liping Zhang Date: Sun, 2 Apr 2017 18:01:33 +0800 Subject: [PATCH] netfilter: ctnetlink: skip dumping expect when nfct_help(ct) is NULL 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 Signed-off-by: Pablo Neira Ayuso --- 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);