From cd5f336f1780cb20e83146cde64d3d5779e175e6 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Sun, 8 Jun 2014 11:41:23 +0200 Subject: [PATCH] netfilter: ctnetlink: fix refcnt leak in dying/unconfirmed list dumper 'last' keeps track of the ct that had its refcnt bumped during previous dump cycle. Thus it must not be overwritten until end-of-function. Another (unrelated, theoretical) issue: Don't attempt to bump refcnt of a conntrack whose reference count is already 0. Such conntrack is being destroyed right now, its memory is freed once we release the percpu dying spinlock. Fixes: b7779d06 ('netfilter: conntrack: spinlock per cpu to protect special lists.') Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_netlink.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index ef0eedd70541..70123f48b6c9 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -1150,7 +1150,7 @@ static int ctnetlink_done_list(struct netlink_callback *cb) static int ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying) { - struct nf_conn *ct, *last = NULL; + struct nf_conn *ct, *last; struct nf_conntrack_tuple_hash *h; struct hlist_nulls_node *n; struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh); @@ -1163,6 +1163,8 @@ ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying if (cb->args[2]) return 0; + last = (struct nf_conn *)cb->args[1]; + for (cpu = cb->args[0]; cpu < nr_cpu_ids; cpu++) { struct ct_pcpu *pcpu; @@ -1171,7 +1173,6 @@ ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu); spin_lock_bh(&pcpu->lock); - last = (struct nf_conn *)cb->args[1]; list = dying ? &pcpu->dying : &pcpu->unconfirmed; restart: hlist_nulls_for_each_entry(h, n, list, hnnode) { @@ -1190,7 +1191,8 @@ restart: ct); rcu_read_unlock(); if (res < 0) { - nf_conntrack_get(&ct->ct_general); + if (!atomic_inc_not_zero(&ct->ct_general.use)) + continue; cb->args[0] = cpu; cb->args[1] = (unsigned long)ct; spin_unlock_bh(&pcpu->lock); -- 2.20.1